definately my favorite of the civ series
The endgames do bog down still, at least on my computer. And depending on how many civs there are and how big the map is, it can take a minute or two. But it's not TOO bad, it doesn't distract me too much.
Some of the good: I really like the way the AI is with the different Civs. It really plays more of a factor in this game. You not only need to watch how you relate to the other civs, but how they relate to each other too. I've found myself having war declared on me by 3 civs because of one bad move with one of them. Yes, this can be a pain, but I love the way it adds to the game. The game play is simply fun, there are less cities overall, but that makes the game focus on each city to make them the best, rather than just having a whole lot of little, unproductive cities.
All in all, definately a good spend. If you like the Civ games, go out and buy this one. If you haven't gotten into them, it might not be the best to start out with, but if you're daring, give it a try.