Great game but it has its flaws.
1) It is a ~8 hour game and by the ~4 hour mark, the people who are clearly going to lose don't want to play any more. I don't think I've ever finished more than one complete game (using the board version). The computer game drastically shortens the time required, but it isn't as fun for some reason.
2) It is too predictable. There are one or two good strategies for each country. Thus every game, everone plays the same as they did last time. It gets quite repetitive. I'd love to see a game with the complexity of Axis and Allies but the randomness of Risk.