Been dry firing it all night and will shoot it tomorrow or Sunday. Magwell is nice. Trigger is an improvement. Otherwise, meh so far.
If it is measurably more accurate I will be happy, but truthfully, nothing it does will likely excite me. I just don't care for small guns anymore. Not the 19M's fault, and others may be better able to appreciate it than me. The ambi slide release is of no benefit to me, and I actually prefer the finger grooves. Go figure.
A 17 frame and 19 slide would be more interesting to me, but really, the 17 is a pretty sweet spot for me.
I'll update with some shooting in the next few days.