I have very mixed feelings about this game. On the one hand it is absolutely brilliantly designed and really challenges the player. On the other hand it takes sooooo long and has a tendency to lead to analysis paralysis. But lets focus on the good stuff first:
It looks very good without trying too hard which gives it a mature look. Apart from the squiggly writing on the board this game is a perfect example of where style wasn't chosen over substance but still it looks really good.
If you hate having a game being decided by good or bad luck as much as I do then this game is great for you too. Normally the downside of a lack of luck and randomness is decreased replayability but that isn't the case with this game because there are so many options. Since the game takes very very long I haven't played it enough to really find out if best practices will turn up that will make games more similar but playing with different factions and players should keep the game fresh.
The choices you have to make are interesting and anticipating your opponents move is as important as planning your own.
The game also has several balancing mechanisms where the seemingly runaway winner can get dragged down in the mud and suddenly end last. This game somehow perfectly mixes the need to play well consistently throughout the game but still leaves victory up for grabs till the last turn.
The different factions are also well balanced. This is especially impressive since the starting positions are so different and the victory conditions to a lesser extend as well. Also the tactics and areas to focus on for the different factions adds to replayability and depth of the game. The only faction that can be annoying to play is the Catholics since their role is largely confined to just trying to keep hold of what they've got instead of exiting new conquests.
The game scales well and works with any number of players. It even works fairly well as a solitaire experience.
The game is very inaccessible to new players. Although the rules aren't really that hard I find I need to constantly check little things. I recommend practice playing through the first two turns just to get the hang of things and begin to understand what needs to be done to do well in the game. Some of the rules are disproportionately elaborate and long for the role they play in the game. (Yeah mr. Overflow I'm talking to you and also to a lesser extend the Waterbeggars)
The game requires a lot of anticipating and calculating what your opponents will do. Normally this is a good thing but here there is also actual mathematical calculating involved which can get quite tedious and can really slow the game down. The main problem with this is that while calculating all the different possible resource placements and their outcome is very important for the interesting strategical choices, it's plain boring for the other players.
As already noted this game takes ever so long a time to play through. Either this time goes by almost unnoticed because the turns are split into so many phases where you don't really do all that much but all the little decision hang together nicely or the game grinds to a halt and can become a drag when people start taking too much time to ponder their decisions.
Because the game is quite complex and there are a lot of options to go over the social dimension of the game is somewhat diminished. Ardent discussion can get distracting and slow the game down even more. The game is interesting enough that it doesn't really need the social aspect that much. Unlike games like risk and diplomacy which would fall to the level of Yahtzee and tic-tac-toe without it this game does fine on its own. This is also why the two player version also works great because the game mechanics still harness the feeling of playing with more players but results in less down time per person.
Another advantage of the two player game is increased historical accuracy. I found some of the gameplay mechanics, although well designed, skewed from a historical and common sense point of view. A lot of the games I played had the Catholics and the Habsburghs fighting it out in the south while the urban Burgers were at the mercy of reformer influence. The maximum amount of resource counters available in the game works very to create interesting dilemma's but this and the turn order mechanics make it sensible to sabotage your own progress in order to peak in the last turn. Leaving cities unoccupied so there's no use besieging them also feels a bit weird (and gamey)
All things considered I think this game is brilliant but certainly not for everyone. If you want a fast game or one that focuses more on social interaction then strategical decision making this game is not for you. If you like tantalizing decisions and don't mind taking half a day just to finish one session than I would definitely recommend this game. As for me the best way to describe this game is like multiplayer chess without a clock. It has the strategic anticipation and calculation of chess multiplied by the number of players plus a lot of depth but just as in a chess game it gets ruined once your opponent starts to taking too long to make his moves. Just as in chess I probably admire this game more than I enjoy it. But I have to add I admire it a damn lot.
"Half a day just to finish one session"? I've played many times with many different players, including one AP-prone individual in particular, and the game has never run that long. With the one aforementioned individual, I have considered implementing a timer to encourage speedier play but I haven't found it necessary yet.
I agree with the Water beggars rules being more involved and elaborate than the role they tend to play, but I've heard other groups use the beggars more extensively than mine so who knows. The rule for Overflow is fairly short and straightforward though, so I don't see the issue with it.
After a 2-player PBeM game several years back, the multiplayer chess correlation came to mind so I found it intriguing that you mention the same thing. The 2-player game is fascinating for the exact reasons you mention, but it also teaches you how much negotiations can help in this game despite how often they are overlooked. The nice thing is that negotiations must be public at the table, which helps to prevent them from doubling the length of play.
Nice, well-reasoned review of this brilliant game.
My experience with game length has been the same: games with players who must explore every branch of the decision tree make for a long game. There are many decisions to make. I have played the game in much less time than half a day. All depends on who you are playing with.
What I do love about this game is that the theme and design is very mature and accessible (at least in the Netherlands). There are no flashy miniatures, fantasy stuff or hardcore wargaming that might scare away some people. Which makes it possible to play with quite a lot of different people. This has resulted in the fact that in most games I played we either had new players in it to slow the game down or someone who deliberated so long on all his options that you'd quite expect him to come up with a breakthrough in mathematical science instead of deciding to place three instead of two units in some area. (although in all honesty I'm probably just as bad when it's my turn)
Another reason why our games might be a little slower is that the players I play most regularly with tend to play cutthroat style by which I mean that promises are quite easily broken if this is advantageous. Since this game works in a sequential way there's no guarantee that another person will keep his end of a deal. If this trust is lacking or there hasn't been any negotiation the game also slows down because instead of being able to trust that a player will act in a certain way, you'll have to calculate several possible moves he might make.
I found it quite paradoxical that the rules aren't really that tricky and there's not a million exceptions but still I feel the need to constantly check little details. This is probably just because I don't play the game regularly enough to be confident that I know all aspects of the rules by heart. Maybe I'm stuck in a vicious cycle because I don't get to play the game that often because it takes so long and there's usually quite a long time in between games which is why I haven't developed the familiarity with the game that I do have with some much more complex games that I used to play very often and makes them go much faster.
This is really what bums me out about the long game time that it stops me from playing the game very often. I don't even try to put this game on the table on a week day because unless you start very early or your fellow players don't particularly care about showing up fresh and rested for work, I find it hard to finish one session in an evening. And even on days where you do have more time it still is not a game that's likely to make you set up a new game straight after finishing the last one.
It's not a game for all occasions therefore I wouldn't recommend it as your bread and butter game but is a great one for when you have a bit more time on your hands because it's:
1. Truly brilliant
2. Scales well for different numbers of players
3. Is accessible to a wider variety of people than is usual for a game of this level of complexity and depth.