The main thing I like about the 90mm, and something I like about all the Fuji primes, is that it can be used with a wide open aperture without loss of quality, and that is where I tend to shoot it and all the other Fuji primes when doing lifestyle photo shoots. I like using the selective focus that comes with an open aperture and the softness it gives to a photo. Somehow they seem more candid when shot that way.
Another aspect of the 90mm lens that helps adds to its usefulness is that it can focus so close. I find myself using it instead of a macro on still life subjects for the same reasons of selective focus.
The third aspect I like of the 90mm focal length is that at a full frame equivalency of 135mm it borders on delivering a telephoto effect of compressed space giving the shots more of a candid look.
Our model for the this shoot is also a hand model so I found myself doing a lot of close up work and used the 90mm whenever I could. Even the Fuji 56mm f/1.2 cannot focus as close as the 90mm (.09x magnification at 2.3' for the 56mm as opposed to .2x magnification at 1.97' for the 90mm).