I bought this with my Fuji S5 Pro to use for semi pro work, such as weddings, after discussing the option of the 17-55mm f2.8 with the sales guy in Calumet. He told me that I would be very happy with the 18-70 and he was not wrong! I also bought the 50mm f1.8 D lens to use for portraits and low light shots and this complements the 18-70 very well indeed.
This lens is far better than the average kit lens even though it was initially introduced as one. It is nice and sharp, good quality build with a good build quality to weight ratio, not too heavy, not too light although I do admit preferring heavier lenses to light ones.
I am very impressed by the performance and as someone else said here, this is a gem of a lens for the money. Slight vignetting at 18mm wide open, but nothing that cannot be fixed easily with Photoshop.