versedmb wrote in post #4415040
I realize that the build quality of the new 18-55 is likely not great and the front element rotates, but the Photozone testing showed their copy to be about as sharp as the 17-55 IS and I know many pros who use this lens for weddings, studio work, landscapes, etc. I realize that its not f/2.8, but used for handheld landscape shots it might give nice results.
Yes its a great little lens, no major problems with it, its not in the same league as my L but you would hope it wouldnt be because otherwise why would anyone pay so much for L lenses.
While it is very sharp for a lens of this price, there are so many other factors that make for a good image, for money shots I would always ALWAYS use the 24-105L that I own, not because I couldnt do the same with say the 18-55IS, but I can guarantee the results with the L, the same reason why I would chose the Canon 18-55IS over the Tamron, if AF accuracy is only a little better on the Canon then I would chose that, providing of course I didnt require f/2.8 of course 
Ive owned an f/2.8 lens, its obviously faster than say f/4.0 or in the case of the 18-55IS f/3.5-5.6, but for low light I still get more keepers with a slow IS lens than I do a fast non IS lens, f/2.8 is not what I class as fast glass, its "faster" glass, f/1.4 is fast.