I've been using the Fuji X-T1 for a while now and although I can't bring myself to selling off my Nikon gear and I haven't touched the Nikon since I got it, I am loving it. Let's summarize my feelings. My wife says I should talk about my feelings more often, so here we go!
The camera feels great. Love the controls now that I'm getting used to them. I will admit, it's not as comfortable for me as a Nikon ergonomically, but I've been using Nikon for a long time. The camera is light and I can carry it around all day with no problems with the 18-55 lens on it and the little Nissin flash. The Nikon with the equivalent lens and my monster SB-910 will start to hurt my back after an hour or so.
The Fuji is great with my adapted Nikon lenses and manual focusing. The focus peaking is clear and the viewfinder is a lot better than I thought it would be. The Fotodiox adapter does exactly what it is supposed to do and mates the Nikon lenses to the camera brilliantly. I don't notice any type of image degradation compared to the Nikon and actually, because of the Fuji sensor, I think they look better. That of course, is most likely pure emotion speaking...
Image quality is top notch. I have no complaints. Low light capability is wonderful. When it does get noise, it is "like film". I quoted that, because I keep reading and hearing it in other reviews, but I'll be damned if it's not true! It really is different than a standard sensor. Don't know why, but hey, fist bump... Kudos to Fuji!
Flash. Strobist. Speedlight... Well, well. Here's a jumble of those feeling things. I've gone back and forth about how this thing supports flash and as of a couple weeks ago, I'm now almost satisfied that this little guy can meet my needs. Here's my thought process for what I need. I sold all of my studio lights years ago, so I now just use speedlights. I need decent powered speedlights that will trigger with some type of radio gadget. For studio (mostly portraits), I shoot manual across the board. Being able to control the flashes from the camera trigger is a big plus. I think I can get that with the Cactus V6 triggers. This is good.
Event and indoor photos in general, while on the move require TTL (or Auto Mode). I can use the Nissin for TTL. It's small and light and works great, although it's no powerhouse and bouncing is limited due to not having an over abundance of extra light to cast out of it's little bulb. When needed, a cute little trick is I can put my SB-910 on my tiny little Fuji, set the flash for auto. set the ISO on the flash and boom, I have tons of light. To move it off camera, I can do the same thing. Either use a cable or a trigger and set the flash to Auto Mode if needed, but I hardly ever do that. Auto on camera because I'm running round chasing stuff or manual, because if I have time to set up the flash, I have time to set the flash power.
Now, the only big deal functionality issue I have. Max sync speed is 180. No high speed sync. Sad puppy... Why is that you may ask. If you need to fill flash in bright daylight, it is really, really hard to get the shutter speed down that low without an ND filter. If you do mostly people work, like I do, you are also trying to get the shutter speed down with a wide open aperture. This is not fun and honestly, my only serious issue I have with the camera and why I am having a hard time selling my Nikon.
I only have one one Fuji lens and although it's not a fast lens, I have no complaints. the 18-55 stays on my camera 95% of the time. When I need shallow DoF for portraits, I stick an adapter on one of my Nikon lenses and go to town. Can't really complain about that too much. I do remember a time before auto focus was all the rage.
Not really sure what else to say. The camera is built well, small and light, takes fantastic photos when the guy behind the viewfinder is having a good day. What more could I ask for? I am glad I purchased it, it is so, so close to replacing my Nikon, it's scary. Fuji is great at listening to its customers and moves forward without wallowing it it's name. Every firmware upgrade has significantly made the camera better than it was before. They haven't only added bug fixes, they've added functionality improving and even adding features. Unfortunately, I can't say that about any Nikon camera I've owned. They usually add lens comparability and bug fixes and they are usually very slow to release.
You may notice, I don't go into movie mode, JPG quality, in camera editing and all that extra stuff. I just don't use it and don't care. I set the camera up once. Make it shoot RAW, then adjust shutter speed, aperture and ISO to take pictures. I'm a simple guy so if you need opinions on that kind of thing, you'll have to try somewhere else. I just don't use any of it, so I have absolutely no opinion on any of it.
If I had the cash, I'd buy another one and all the accessories and lenses to go with it. I don't have any interest in the new Nikon cameras coming out. I don't know that I can ever go back fully. If the X-T2 fills the gaps, I'll scrape and save to get one and move over completely.