I recently played a game with 3 people and indeed it was much more rewarding than my last time with 5 -with 5 the game seems to end too abruptly, without giving the players the chance to develop their strategy, whereas with 3 there were rounds enough for us all
I still have to play it with 4 or 2, so I can't tell you on that.
My first game was with 2 and it was pretty neat. My friend and I both thought it would be better with more players. I've played twice with 4 now, and I'm not sure I liked it much. I'd like to try it with three.