I've skimmed through the reviews and scoured the personal comments, and carefully organized some key quotations to bring you the important things you need to know and what other people think about Condottiere. Perhaps you could call this a kind of "consensus of opinion" - biased of course, because I'm the one who gets to pick the quotes to include. Nevertheless, here you have it, an at-a-glance overview of some of the majority opinions that you need to know about this game.

1. It has a lot of game in a small and easy to learn package.
"Little gem, high potential, easy yet deep."
"Simply a very portable and deep game that scratches a whole lot of itches"
"It's highly portable in its box, and makes for a nice time filler. It's a little easier to get people to play than some of the other games, and it seems easier for many to grasp at its concepts."
"Condottiere takes a simple concept, with easy to use cards, and allows play of them in clever, interesting ways. There is a luck factor, and a bad hand can only be played so many ways; but the game is quick enough to be enjoyable. An enjoyable, light card game - Condottiere is one that will appeal to gamers, especially when in a group of five or six."
"Simple rules, only a few types of cards to understand, but they work together in interesting ways."
"Lots of game packed into a filler time length, and great components to boot."
"One of my favorites due to the ease of teaching and quick game play; lots of bluffing and diplomacy with a nice strategic element thrown in with the mapboard."
"This is SUCH a great game! The rules so simple but the card play and strategy is amazing. It has real aspect of poker combined with a geography element that poker and other card games lack."
"The game has simple rules, great opportunities for communicating/bluffing with your plays, and (for a cardgame) a lot of strategic thinking."
"Elegant area control hand management card game. Although this is in fact a card game disguised as a boardgame, the beautiful board still does add something to the game."

2. It's best with four or five players, okay with three players, and is far from ideal with two or six players.
"Two-player game literally sucks. The whole idea of passing gets kinda lost because, when passing, the other player plays rest of his cards. And because he runs out of cards, new cards are dealt. Passing just gives the other player the opportunity to load the table full of his cards."
"In my experience, the game plays best with 4, and 2 and 6 should be avoided since it's either too slow, or too simple."
"I think the fun level of the game differs greatly depending on how many people are playing. I would give it a rating of 2 when playing with two players. I give it about a 5 with three players. It gets a solid 9 with four or five players and drops slightly to 7 with six players (starts to get long). "
"This game is pretty wretched with 2 players. "
"Condottiere is a decent game with three or four players, especially as it finishes in about half an hour. However, with five or six the game seems to work especially well, as cards such as winter and spring have greater and far-reaching effects. "
"Don't play the game with six players. The game is best with only four or five!"
"While presenting itself as a game for 2 to 6 players, I find that two player games are essentially boring. Because the possibility of forcing a second battle in a round by passing is essentially removed in a two player game (the other player plays out his mercenary cards if you pass) the game devolves into a luck fest quickly. Conversely, a six player game moves too slowly and because you can exhaust your cards in an early battle, players can often find themselves doing something that is not typical of Euro design: watching other people play a game you aren’t playing in. But for three to five players? Condottiere is a great little game that suddenly has taken on elements of bluffing, strategy, psychology at the table and fairly deep strategy in terms of overall position and tactical play."
"This game is about perfect for 4 or 5 players. But with just 3 it doesn't work at all."
"I find that it is best with 4 to 6 players, 3 is ok and with 2 you loose the inter-player bickering and deal making that I find most enjoyable. "
"It's best with 4+ players."
"Not very good (virtually unplayable without some house rules) with two players, but an excellent outwit and outbluff your opponent game with 3 or more."

3. The game has randomness, but it is mitigated by good hand management and the quick play time.
"The randomness is the game’s main downside. All card games suffer from this problem to one extent or another, but Condottiere is quite prone to dealing out useless and godly hands. Fortunately, each game goes on for multiple hands and usually two or three rounds of cards, so the luck often balances out."
"I also don't believe it to have a high luck factor. Rather than compare it to war, I would compare it to poker. You don't always get dealt high cards, but knowing when to bid and how much makes all the difference in the world. "
"I like that it's possible to win even when you have a bad hand of cards. (But of course some hands just can't be saved.)"
"In the interests of play balance, we instituted the following house rule: players only get 1 extra card (not 2) for each territory they control. Otherwise, players who take territories in the first round have a far too overwhelming of an advantage. "

4. The bottom line: what you need to know.
Especially for four or five players, this is a quick little card game that offers a lot of replayability and strategy in a small package.

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The complete list of Ender's "What you need to know and what people think about..." reviews:
http://www.boardgamegeek.com/geeklist/37595