Got mine last night and it is amazing.
As some people has been saying, it doesn't really look blue. Most of the time it looks kind of grey. The materials are, as everyone knows, all plastic. It feels good on the hand and very light (which is important for me because I normally put it on my shirt pocket). The back cover is very thin but I don't particularly mind although I can see why some might not like it.
The screen is great, high res and vibrant colors. HD videos look pretty cool, including youtube HD.
It does sound good, I haven't had the chance to test it with my Sennheiser headphones but normal earbuds sound great.
The phone is unbelievably snappy. I'm coming from a I9000 and also have an iPhone 4 so it was kind of a big step up. I normally read ebooks on the kindle app and on other devices it was a bit of a pain to leave the app to answer a text or something similar. Not anymore. It responds very good.
The movement gestures (direct call, smart alert, etc) work pretty well too.
The only thing I'm not so happy about is touchwiz. On my I9000 I was running a custom rom (slim) that was pretty close to stock performance and I sorely miss it. There are options right now to flash the phone but I want to make sure there are no issues before voiding my warranty.
In short:
Pros: Fast, comfortable
Cons: Touchwiz