I prefer it with three but it plays perfectly well with two. I know some people suggest reducing the map size with only two players but I don't think that is necessary unless you feel the need to increase the likelihood of conflict (which is still pretty likely anyway, in my experience).
The 2p game is okay with the normal map, but when we tried taking away the top and bottom rows (i.e. deal out 4-5-4 instead of 3-4-5-4-3), everything 'clicked'-- the balance felt just like 3p, which was my favorite player count for the game before. Highly recommended.