Just from what I've seen:
- No seeds grow; I can plant them and they will not reach maturity unless bonemeal is used on them, and anything resistant to bonemeal (pumpkin blocks, melon blocks, sugarcane, cactus, etc) does not grow at all. I can also agree that the grass does not grow back on top of the dirt when cut or grazed as well.
- Yeahhh, the poor Nether... xD
- No monsters are spawning at night or in dark areas. I've since killed the ones that remained in my area and underground that I've found from the rollover and no new ones have spawned.
- The map is completely empty, and by empty it says it is unexplored no matter where I am standing (my house, the spawn point, market, towns, etc).
EDIT: So I found a spider outside my farm just now that -attempted- to be hostile... and by attempted I mean it jumped at me twice, I swung at it twice, then it just became braindead! He just sits in there with the cows and mingles now, I like passive spiders! Awww, he's so cuuuute C: