I bought my SGSII yesterday from HV_Thugg (thanks man.. really tricked it out since)
Hands-on
my initial feel of it is that it had a big - beautiful screen, it felt light and was insanely thin.. the battery cover felt like a little piece of plastic which gave me the impression of cheapness as well as the vibration i phone when tapping the phone - like the captivate - which made me think the phone was delicate. the phone moves very fast - no lag whatsoever with live wallpaper or with dynamic effects enabled. and note that this is all stock!! after rooting the phone and loaded up a CWM infused kernel and loaded a Cyanogenmod 7 nightly (Cant do better for now)
The phone is relatively easier to root than its predecessor, i have less of a fear with bricking and allows for easier customization and alot of other things that would be more difficult on a i897.
Features
Camera is AMAZING!! picture quality i can say is similar to that of a 6MP digital camera (which is alot to say cuz digital cameras are MWAR better than phone cameras.) and the flash is bright and focuses on the right areas when taking pics.
the 1GB RAM is definitely observed in its speed and the processor kicks *** when surfing the net and playing games. The phone is speedier than ever and cuts through graphical games like backstab HD like butter (which i must say is impressive) unfortunately, i am not so impressed with mali-400 MP's rendering capabilities.. i saw better rendering from the ULP Geforce GPU on the G2x.
Overall
Phone is amazing.. not sure if it is worth the price tag as yet but i must say its a definite improvement over its predecessor and deserves its ratings if not the $600+ price tag.. a definate keeper in my book.. i'm gunna keep this bad boy untill next year when the SGSIII comes out