Oops, posted this in the wrong thread yesterday, meant to put it in this one:
I gave in and eventually got a Pro Controller myself. On the one hand, it does feel really nice in the hand. Probably would put it second right after my Xbox One Elite controller (which is not a fair comparison at all when you consider the price of the Elite controller).
That being said, I play about 70-80% of the time in handheld. It really messes with my muscle memory when I attempt to spend that other 20-30% of the time (docked) with the Pro Controller. Things that I'm used to doing (and have already mentally compensated for) with the Joy Cons just feel off when using the Pro Controller to do the same thing. If I just use the Joycons (split) all the time, then I obviously don't have that problem.
The end result is that I barely use my Pro Controller.
(I've also read that some people have issues with the D-pad, but I honestly haven't used the Pro Controller with any of the 2D games where D-pad accuracy would be key.)