Dad has both (apparently, along w. my childhood chore of cleaning guns, I now am supposed to break in his new carry guns for him. Not all bad, except for the tiny monsters...)
The G36 is a bit bigger, but MUCH easier to shoot, at least for me.
The PM45 is conceivable as a pocket pistol, and serves its purpose for him - securely stored in a town that he flies to from time to time, so he doesn't have to hassle w. flying w. a gun. The G36 is pretty much a waist pistol.
IMO, the first thing to address would be any sharp edges on the trigger - Dad's had some. Otherwise, learning to deal w. the recoil would be about it - I actually didn't mind the stock sights. As I recall, the trigger pull feels a bit heavy, and is longer than the Glock - not really a problem, provided you're used to a DAO gun. It is considerably harder to rack than the G36, but that shouldn't be much of a problem for a healthy male.
Personally, I've gone w. a 329 NG for my gun of ~ that size. I just use a clip draw to carry it, and have some custom "service style" grips fitted to it. It's been quite comfortable, and has decent sights, has a remarkably smooth, if heavy, trigger pull for a stock revolver, and is comparable in weight to the Glock.
