The width is not a problem it's the height. I don't think that height fits in most standard fridges. Also, the drain is too low and once it's full it's nearly impossible to move. So filling and emptying it while it's in the fridge sound like a real PITA.
I don't see a significant advantage over something as cheap as a pair of better bottles or even some plastic buckets.
Well, as outlined, it fits in a standard fridge (as arturo pointed out, I'm sure it's a major design criteria of people making homebrew equipment to have their stuff work with what your average person will have access to.)
In terms of the benefits over Better Bottles/carboys, the main ones for me would be:
a) Get a full 10-gallon batch in one vessel. (no more having to split yeasts, worrying about one half turning out different than the other, etc.)
b) Dumping trub - I use a plate chiller, so my fermenters end up with lots of cold break, in addition to the usual trub. Being able to just ditch all that after it settles out 12 hours into fermentation is nice.
c) Harvesting yeast (yes, doable with any vessel with effort and patience, but being able to easily snag a jar of yeast will help something like this pay for itself over time!)
d) The ability to push via CO2 means I can run the beer through a filter on the way to the corny (Right now if I filter I have to rack to a corny, then push from there to ANOTHER corny)
e) Stainless, so it's sanitary, scratch resistant, and no light can pass through
f) Easy to open up and clean (scrubbing kreusen off the domed upper part of a Better Bottle, especially one that's a bit warped from having hot PBW put in there, is a royal PITA!)
I know a lot of people ferment in sankes, which address several of the issues above (being able to push with CO2, having a sealed, stainless environment, full batch in one vessel) but the ability to dump trub and harvest yeast are big for me, as well as the ability to open the whole thing up and thoroughly clean it.