This is a great little lens if you want something compact and unobtrusive. I use it with an X-Pro1 body and an X-T1. It's not stunningly sharp wide open - but quite acceptable and stopped down a bit it's great. I've knocked off one star because it's a little soft at f2.8 and it has no aperture ring which makes operation slightly more frustrating.
So small: you can leave it on as like a lens cap and be always ready. Gives the XT-1 a very thin profile. An XT-1 can certainly be carried under a jacket (around your neck) if not really in a pocket with this lens.
My personal 'fun' camera is currently a Fuji X-E1. (my job is in the photography industry using big & heavy professional DSLRs all day long - so the Fuji system what I use for my own photography - landscapes, family, hols etc. mainly - when not at work)
Before that I used a Fuji X100 but I sold it and upgraded to the X-E1 which came with the excellent Fuji 18-55mm kit lens.
However, I found I wasn't enjoying using the X-E1 anywhere near as much as the old X100 and this was due to the extra weight of the 18-55mm and the fact, using primes most of the time before, I just didn't like the experience of using a short zoom lens. It was always either at 18mm or 55mm (never anywhere in between) so was being used like a couple of primes anyway.... and that weighty 18-55mm made the X-E1 feel quite 'front heavy' especially when zoomed out.
The perfect solution is this 27mm f/2.8. I won't go into detail on the sharpness and speed of it - others have done that over and over - needless to say it is fine and on a par with the X100's lens (apart from the X100's f/2.0 aperture which was quite soft anyway).
What I will say is my XE-1 is now much more like my X100 now - handy, creative, well balanced (weight), light and fun to use once again.
An X-E1 with this lens is just like having a slightly more robust X100 with a slightly longer focal length (I like that) and the advantage of a built in flash which can be bounced (just hold it back once popped up) plus the ability to use other lenses in the future if needed.
Handling wise, many bemoan the lack of a aperture ring on the 27mm but quite honestly I prefer it this way. I don't use aperture rings on any of my company's DSLRs - rather the dial on back as most lenses now come without an aperture ring - and now this is how my X-E1 works too - perfect and familiar for me.
Don't get me wrong, I like the retro feel of the system but of all the 'old school' things, the aperture ring is the one thing I wasn't glad to see making a comeback - I've always found them awkward compared to thumb wheel on the camera. That's just me - you might disagree.
Finally I don't use my Fuji for videography, but if I did, this lens would NOT work very well. It makes a noise when it autofocuses and even when it is manually focused (which would be picked up my the camera's Mic) and it doesn't have have VR (vibration reduction or whatever Fuji call it) which would count against it for steady, hand held, videos.
However I'd recommend this lens 100% if you want to make your Fuji CSC very compact and X100ish and you're not bothered about video.
crisper than my 18-135 WARNING: don't buy this lens for video, the autofocus (and even the manual) is horrifically loud. you can't use the natural audio you used when filming because it's making noise almost constantly.