Both The City and The Castle are very similar Carcassonne games that ease tile placement while adding extra rules that differentiate them from the regular Carcassonne game. I like both of these games better than base Carcassonne, as I feel that they offer a bit more strategy.

These games are different from regular Carcassonne in that the only tile features that must match are the roads. This generally allows for a higher number of places that a tile can go and seems to encourage player interaction by cutting off other players. Both games also have borders that come into play and limit the direction that the city can expand in. This changes the strategy of the game quite a bit as it restricts how large some structures can be.

So how do these two games differ from one another? The most obvious difference is that The Castle is only for two players, while The City can hold up to 4. Having played The City a few times, I see no reason why it couldn't support 5 or 6 if you have the extra meeples from other Carcassonne games. The tile placement is very similar, but the actual scoring of the two games is a bit different (I won't go into the details here, as that info is easily found elsewhere.)

Another difference is that the walls in The Castle are predetermined. This could be a good thing as it allows you to play on a medium sized table right up to the edge without concern for the tiles overfilling the table space. One of my few complaints of The City is that the tiles often become placed towards one side of the table, requiring the entire set of tiles to pushed towards one side of the table. The City does have more strategy to it, and part of this is the fact that wall placement is done by players and not predetermined. This is one of my favorite aspects of The City, but it does require a bit more table space. The ability to place spires along the wall for points and the option of placing Meeples as guards on the wall add even more choices without overcomplicating the game.

As far as components go, I think The City is a clear winner. It comes in a beautiful wooden box, has great looking tiles, and the wooden walls add a lot to the look of the game. The city fills up nicely and looks great when it is finished. The Castle is not badly produced, but it is much more standard fare. The tiles are more clearly colored with bright reds and grays, but it looks less impressive when done. The tiles might be a touch more clear than the muted colors of the City, but the overall appearance at the end is much less impressive. Part of the scoring in The Castle is the left over space in the city, but it does cause the board to look somehow incomplete at the end of the game.

So... Which to get? If you hate carcassonne, don't come near either of these. They don't change the underlying play of drawing and placing tiles (and I have no idea why you read this!)
If you enjoy Carc but would like a bit more strategy, both of these are great games. If you are a gamer on a tight budget and exclusively play with 2 players, The Castle is a great game at a good price. Its only downside is that I feel it has almost been made obsolete by The City. If you can afford the 30-50 bucks it costs, I highly recommend The City as the game to get. I feel that it is much better than The Castle due to its increased number of placement options, the ability to place the walls, the incredibly nice components, the higher number of players, and overall feel of the game make it one of my favorite games. It is slightly more complicated than other Carc games, but only slightly so. If you have any desire to play with more than 2 players and are looking for a Carc game, The City is a can't miss winner.