No offense, but why should you care if Pros use it? What kind of pros? PJs? Sports shooters? Wedding photogs (many of whom are not actually "pros")? Portraiters (is that a word?). What do you want to use it for?
Any rate, I have one, and am decidedly an amateur. I used it as my only camera for a trip to the Cayman Islands, and was not at all disappointed. I liked it so much, it replaced all my m43 gear! (I had m43 for its size, and the RX100 is much more compact, and close enough to m43, and even better in some ways. I also have other cameras, though. Not sure I'd have the RX100 as my "only" camera if I could only have one).
Just understand what you get with it -- deep DOF, pocket sized camera, clean ISO. DR is not it's strength, but it's got the best DR (when shot in Raw) of any pocket camera with a zoom lens. In fact, I don't remember anyone moving away from the RX100 due to it's image quality. It's almost always been due to ergonomics or controls. The RX100 is a small camera with few direct controls. But then again, the sensor is so small that DOF is pretty much a non-issue, and the IS is great, that most of my exposure controls that I like to access are EV (which is 1-button access), AE lock (1-button access) or sometimes shutter speed, if I want to make sure I freeze motion.
The other controls I use regularly on the RX100 are sweep pano (on the mode dial), water color effect (behind the fn button) and auto HDR (also behind the fn button). The one complaint I have on the mk1 is that you have to put the camera into jpg mode to shoot auto HDR or water color. Other than that, I shoot mostly in P mode, and am rarely disappointed. As I mentioned above, though, jpg out of camera has about 2 stops lower DR, so Raw is important to use (this is for the mk1, not the mk2). One last comment -- it tends to be very conservative in metering to protect highlights. So, in situations where DR is pretty even, I tend to go as high as +1 EV, otherwise the scene looks a little dark. In very contrasty scenes, I'll use AEL to get the exposure I want, or switch to auto HDR.
This is my main camera for video. With deep DOF, I rarely have to worry about focus. But, there are no "pro" video options here. It's just the best point and shoot video out there.
So, to answer your questions directly
(1) Does it have good image quality -- yes, very good. And outstanding for it's size. It's high ISO is cleaner (though less detailed) than my APS-C sized EOS-M
(2) Does it have decent D/R - yes, when shot in RAW. JPG DR is weak (on the mk1)
(3) Does it shoot good quality video - yes, reasonably good, and the best point and shoot in my experience.