My current 'standard’ by which everything is measured is an older (99) Interarms Walther P99 .40. I owned this Walther since before I started keeping accurate round counts, but it has somewhere between 7500 and 8000 rounds through it. It has had one single failure out of all those rounds, which was a failure to fire on some rather hard primer ammo which was solved with a second trigger pull. Amazingly, the weapon looks like it has no more than 100 rounds through it.
The recoil is noticeably harsher than my USP .45 and slightly worse than my USP Compact in .357sig.
I’ve seen many of the more recent P99s and they have been fairly crappy by comparison.
The newer ones have a problem with magazine floor plate failures. I believe there was an Air Marshal whose P99 or SW equivalent dumped its rounds as he was boarding a flight. Luckily, the new magazine I bought just disassembled itself while sitting on my desk rather than in my weapon. Needless to say, I was none too pleased.
There were some major speed bumps when S&W got their hands in the mix with Walther. I know a friend of mine had a recent PPK/S that was shooting two full feet left at 20 feet. I’ve seen the slide coatings come off with the scrape of a fingernail. Apparently these problems have been rectified, but it still lost my ‘warm fuzzy’ for recent "Walther" products.
While I’d take the P99C over the M&PC simply because I don’t like glock action pistols in my pocket, I think the M&P is superior to the full size P99…
YMMV
