Yeah, I agree about ugly post searing Ascalon. The new area looks pretty though. Hopefully it doesn't get thrashed.
A quick list of new stuff:
-Battle Isle
1. Temple of Balthazar
a. Isle of the Nameless
b. Daishezen Challenge
-Two new classes
a. Assassin
b. Ritualist
Daishazen and the Temple are little pvp towns, Isle of the Nameless is an instance. From the Challenge area you can select different challegnes versus computer pvp teams based on popular pvp builds(obsidian flame spike, IWAY, trapper, Smite monk).
Within this area, and the other arenas there are new arena maps and old maps now used. Ascalon and Yaks arena now appear in random arena battles. The new arena has flags and an obelisk.
Team Arena, Random Arena and Tombs(now called Heroes Ascent) all have new looks to them. The unworthies in tombs are also redone and now resurrect.
Two new classes with availability of seemingly all their skills(if you could afford through faction). New prebuilds to go along with the new classes as well. Unfortunately, it seems ANet has made a poor decision and added a nerfing to faction farming during the weekend, mostly leaving the majority of players to be stuck with crappy prebuilds. The Rit/Mes prebuild is especially lame. I have a lot of faction, I had 10k readyt o spend but I quickly ran out and it's been harder than normal to replenish it so I can expirement with skill combos. I've hardly touched ritualist, because straight spirit spamming is boring and if I want to do something else I'm going to have to spend a lot of faction.
One major downfall of the preview weekend: LAG! Serious lag issues from all the free demo users. GVG I just had to give up on, the lag is screwing up coordination.