Canon's tech demos make the rate at which they dribble technologies into their cameras all the more frustrating. Hopefully the attention Sony are getting will light a fire under them.
I don't doubt every manufacturer does to this to a degree, but Canon is absurd and unsubtle about it. The whole thing left such a bad taste in my mouth that it would be almost impossible for them to get me back as a "fan" at this point, even if they stopped doing this.
So... All of them? There are only about a dozen FE lenses released. The 3 Loxia lenses, the 2 Batis lenses, and the Sony 28, 35/1.4, 35/2, 55, 90, and the 4 zooms.
That's basically the extent of the Sony FE system, which is still rather lacking compared to Nikon or Canon's 100-200 lenses.
Also the Sony 35/2, 55, 70-200, 28-70mm, 16-35mm and the 28.
When I do the specific count, "about a dozen" comes to 11.
I still have and use a fair number of Canon lenses with my Sony gear (using a cheap but effective Commlite EOS->FE adapter), but haven't bought any new Canon lenses since the switch. Obviously I don't count these lenses in my "about a dozen" as they aren't native FE.
I also use a bunch of 80s era Olympus Zuiko lenses with my Sony gear, some Nikon glass and a bunch of oddball Russian lenses.
While the complaint that the FE system is lacking lenses is true in a sense, the short flange distance between the mount and the sensor on the Sony mirrorless cameras means that if you're willing to deal with manual focus (which is pretty damn easy to deal with given the focus peaking abilities of these cameras) you have a whole universe of lens options since you can adapt virtually any lens to these cameras.
If you really need autofocus, you can still adapt a lot of Sony Alpha lenses with pretty decent AF performance via the LAEA4 adapter, and the A7R-II apparently allows for very quick AF with EOS lenses (my Commlite adapter for the A7/A7ii allows autofocus, but it is so slow that manual focus works better most of the time).
How do you like it?
Digital cameras still don't have detailed intervalometers (or even a timer that goes over 30 seconds)? Why don't we have burst modes that can average/median multiple images into one so we get fake long exposures? I can find tens of features I could very easily code, and which firmwares like Magic Lantern have, but that Canon still has not added.
The AF is not great, I always notice myself wanting a bit more sharpness from shots where I wasn't thinking and let the AF do whatever. If I care I manually focus, and then things are sharp even when looking at 3:1 magnification. I've tried a friend's Nikon D750 and was blown away at how fast the AF was compared to Sony's, but I don't know how accurate it was.
The Zeiss-branded Sony lenses are amazing, though there is a limited selection compared to Nikon and Canon, who also make great lenses. Thanks to the missing mirror, you can easily adapt any lens you want onto the Sony body. I use a (manual-focus, of course) Nikon 28mm lens. As I understand it you can adapt Canon lenses to the body and still get EXIF, camera-control of the aperture, and AF, but I haven't tried it.
Software for DSLRs is never good, and Sony is no exception. I don't have a flash attached to my camera, but if I try to turn the flash off (it's currently in "W" mode), the camera says "setting not available in aperture priority mode". The functions you can map to buttons is stupid (no one-button focus magnification, the only option is a two-step operation). Their auto-ISO algorithm also makes stupid decisions when you give it other variables control. Set the lens to f5.6. Point at something bright. It decides ISO 1600 at 1/8000 shutter speed. WHY.
That said, you can basically point the camera at something vaguely interesting and the photographs are great, so I won't complain. I took up medium format photography recently and my list of mistakes is impressive. I have an entire roll of film showing detailed views of my lens cap, for example. I have some other pictures with perfect composition and exposure ... that I forgot to focus. This modern technology is quite useful, even if annoying when you're looking through the EXIF information and thinking "I wish the camera chose ISO 100 here...".
So in the end I like the Sony. And it's sure small and easy to carry around compared to a "real" DSLR, though still more imposing on your subject than a Leica.
Upgrading your camera becomes a frustrating ordeal. Never knowing if you're getting a good deal or you're getting conned.