Quote:"Not always very useful" is answering what, exactly?Stupid quotation system. "Not always very useful" was quoting yourself, and it was the second question. The first one you asked was why the price was higher than comparable Canon EF-S and EF-M options, and then you said the Fuji has a bigger focal range than both and is constant f4 which is a part of explanation. Not to mention the better build quality of the Fuji vs. the EF-S.
F4 compared to f5.6 is not very useful a difference on APS-C with an UWA zoom, in my opinion. You are not gaining a lot of shallow DOF (to say it mildly) and exposure time wise it is still an UWA anyway.
I too have had the crappy put together Tokina 12-24mm f4 (which would have worked just fine on that APS-H camera) and do not get why its constant f4 would be of any advantage.
And that is not worth €600 or €731 to me..
The Tokina does not play exactly well with APS-H sensors, it only starts working without heavy vignetting almost halfway through the range -- I tried.
Re: the shallow DOF... it's not be all end all of photography. A lot of the times... quite the opposite. That's not something I would really want in an ultrawide anyways - maybe there are some very specific usage cases, I can't think of any that would benefit me in my work. You could probably get what you want anyways by focusing close.