My main interest is portrait photography so my comments are based on my usage of the lens, however I have used it for general photography and found it very satisfactory for that as well.
Before buying the 16-55 I took quite a number of sample shots, one advantage of having built up a good relationship with a local camera shop I have supported for a number of years, and compared the results with the 18-55 I owned. I found, others may have found differently, that the 16-55 was visibly sharper wide open. Of course the other advantages were having 16 mm instead of 18 mm at the short end and f2.8 at the long end.
I find that the 16-55 is too sharp at f4 to use on any female subject with less than perfect skin and/or makeup and either a soft focus filter or softening during processing is necessary. Another advantage is that when using the Nikon system, because of the aperture of the 28-105, I also had a 85 mm f1.4 D for shallow dof, owning the 16-55 I see no need for the 56 mm f1.2 and have bought a 90 mm f2 instead.
The only other similar zooms I can compare it with are the two Nikon ones I owned before moving completely to Fuji about a month ago. These were the the 24-85 f3-5-4.5, the discontinued one, not the current version, followed by the 28-105 3.5-4.5, which I bought secondhand in mint condition, after being so disappointed with the 24-120 f4 that I tried. Again others may find the 24-120 perfectly satisfactory, this is only my personal opinion. The Fuji 16-55 outperforms both of them by quite a margin when I look at similar shots taken with the Nikon lenses on my D700 and the 16-55 on my X-T1.
Because of the type of photography I mainly do I don't find the lack of IS to be a problem. I find that the weight of the lens to be an advantage at slower shutter speeds at it seems to make it easier to hold the lens steady, but if anyone regularly shoots in dim conditions requiring shutter speeds below 1/60th then I would recommend that they buy, or stick with if they already have one, the 18-55. I must admit that with the type of photography I do I don't really understand the obsession with IS, as none of the Nikon lenses I used for portraiture, those I mentioned above and the 105 DC I also owned, had it and I never had a problem. There has been a lot of talk about the 16-55 and the lack of IS, but the 56 f1.2 doesn't have it either, so why would the 16-55 be any less difficult to hand hold?
Hope these comments have helped.