I tried it on my laptop, which was a bit slow. Now that Notch has given consent to use the link and confirmed that there's nothing malicious about it, I may as well try to run it on my desktop so that it wont lag so much.
Swamps don't look much like swamps but they do look very nice. However vines + surface lava = lots of fire.
Biomes are much bigger. They're still not as big as I'd like but they'll do. Oceans are huge, it took me about three minutes to cross one in a boat (although, remember, the game was lagging a bit). I didn't find any NPC villages or dungeons, or see any Endermen, which I guess means I need to do some more "bug testing" later.