Managed to test out the Samsung Galaxy W at the Samsung Store in Gardens Mall today.
Build quality is good, feels solid in the hands. Nice texture of the back of the phone for grip. The overall look of the phone is nice, simple and elegant.
I'm also impressed with the display quality of the S-LCD. Colours look vibrant and sharp. Not as saturated and deep as the SAMOLED+ of the SGS II, but natural enough for my liking.
Responsiveness of the touch screen is also pretty good. Swiping across the homescreens with multiple widgets is a breeze. The
3D Swipe thing works decently as well. Not much noticeable lag in the General UI.. so far so good!

Web browsing is the excellent part of this phone(for me). Scrolling and pinch to zoom on web pages like engadget or gsmarena or forum.lowyat.net was silky smooth. I'm amazed how the processor manages to excel in this department very very well. I'd dare to say that the web browsing experience is close to that of the Samsung Galaxy S II.