thanks doodah, that's the answer i am looking for. i know the built is definitely much better judging from the price and thus the material used should be compensating here. vignetting wise, i am not so worries as i always apply the vignet effect coz i love to add a bit of the lomo feel.USM to me is not that important as i am not shooting sport and macro, most of the time i will be shooting friends at wedding or gathering for family. colour and contrast i need to really go and try out myself in order to justify. i am really surprise that the resolution u give it a "SAME" sharpness??? that really surprise me. in this case, i think i should switch my choice to maybe 10-22 to capture wide angle view. tho i own a wide angle converter, the Chromatic Aberration is totally unbearable at times. like u said some of the weaknesses in the kit lens can be easily adjusted in PS, i will wait a little longer to upgrade to this lens when i buy my 5DMII in the future.
thanks alot!!!