Having used an XE-2 for a couple of years (and generally like it), I was interested to try an XE-3 at Photo-Plus Expo in NYC last week. I'll only comment on a few improvements that mattered to me.
1) The XE-3 can now be set to use only the EVF for shooting, and the rear screen for review. This makes it function the same way as all the traditional DSLR's I have used, and which I'm used to. The rear screen does not light up when held away from the body, unless I want it to. Shooting with a camera held out in front of me is not my choice for serious work, anyway; to see the screen clearly, I'd need to put on reading glasses. I believe, but am not certain, that the EVF only powers on when the eye sensor sees my eye at the eyepiece. I believe the new camera should have better battery life solely as a result of this change. The XE-2 cannot be set to operate this way.
2) The XE-3 can now be operated as follows, if you want: Center-point AF focus on the desired sharp feature, hold shutter half-depressed, re-compose as needed, and fire. For one shot, my XE-2 will operate this way, too. BUT, I cannot take a follow-up shot with the XE-2 unless I release the shutter button fully---and then, I have to re-focus and re-compose, or perhaps add a step by pressing a focus lock button. Very annoying! With the new camera, if I keep the shutter button half-depressed, I can press through again for one or more follow-up shots, with my original focus unchanged. This makes for much more fluid work. and fewer missed shots. Again, this is how many, many current pro-level cameras operate. (While I appreciate what good electronic focus systems can do, I almost never allow a camera to decide what should be sharply focused---that's my job.)
Seems to me that both of these changes, while seeming small, are ways to make good tools even better, and to bring them into line with the good features of other serious cameras. The XT-2 with most recent firmware runs this way, too, and perhaps the XPro-2 and Xt-20 as well (?). Yes, I could change the focus point on an XE-3 with the joy-stick, and perhaps the new point would be as sensitive and accurate as the center point. But I might be slower, working that way. I appreciate having the choice.
3) The power switch on the XE-3 is just a tad shorter that the XE-2 version, and does not project out past the face of the camera body quite as much. It seems much less likely to get turned on by accident, compared to my camera. My switch also moves a bit too easily, with the net result that I have often turned the camera on by mistake. Not so good for a camera with rather short battery life. I'm thinking of asking Fuji Service if they can put an XE-3 switch on my XE-2.
Fuji continues to listen to photographers, incorporates good ideas into new models, and probably does more than any current maker to enable updates to older cameras. Combined with knowing the value of old-school aperture and shutter controls, Fuji commands my respect more than other current camera makers.