After flying around in creative for several hours in 4 different test worlds I have observed the following.
New biomes, I like them and the changes to the swamp biome.. its somehow swampier, however the "roofed forest" biome generates far more often then the standard forest. On several world gens I had to search for more than 10 min in creative before I found a chicken and 20 minutes before I found a single stand of suger cane. I don't think they are spawning in the new biomes. Also I had not found a village in any of the new biomes, has anyone found a village in one? If not it might be a bug.
Given the new like-prefers-like biome attachement I think there needs to be a long period background forceing function that pushes hot-warm-cold-warm-hot to make sure varieties get visited. Otherwise the random walk seems to get stuck in a particular zone area and not escape. It would proably make sense to pin the spawn point in warm and make one of EAST/WEST or NORTH/SOUTH a forced temperature cycle so +1000 would put you in different temperature zone.