From the mid seventies to the mid eighties every gun maker that you ever heard of and some you had never heard of came out with what basically was the same type of pistol. It was as if every one came out with a high performance pony car within a certain time period.
This was driven mostly for the NATO contract for a new service pistol but there was also broad interest in law enforcement (world wide) for a gun with similar features. These guns got the nickname of the "Wonder Nines" and some were based on then current designs with single stack mags being replaced by double stack mags and some other added capabilities, to further features and some were brand new designs from top to bottom, designed and built from scratch.
The concept was to have a pistol with high round capacity, 15 rounds was the norm, that weighed fully loaded about the same as a fully loaded 1911.
These guns ranged from being pretty good to very good in just about every aspect. They were mostly reliable as a stone, some had safety and handling locations that differed from the others. It was a real feeling out process and this was before NATO actually started testing these things.
I won't go through the whole process but we all know the Beretta won the NATO battle and even the late coming Ruger P85 and an improved/reconfigured Sig brought in for a new final bit of testing after the Beretta was named the winner and was already being issued to some NATO countries. That second batch of testing was forced by some arm twisting done by mainly politicians and I was involved in that part of the fun and festivities during this time period. We for an actual reversal to occur the two new guns would have to blow away the Beretta in this new batch of testing, they did not, they were good guns but they didn't trounce the M9 with non-stop end zone dances. There was a reason they had to trounce the Beretta and it's both complicated and heavily involves politics at that time and the direction NATO was talking. It really ended up not so much about the gun but where the gun came from.
None the less, NATO ended up with a fine service pistol, the Beretta and things were sort of beautiful in the world. The police/civilian market made some of the losers a lot less unhappy and everyone for the most part made money selling guns based on this original concept, S&W made some changes that they probably should have done in the early portion of all this but they ended with a nice pistol.
The kicker of it all was just as all the niches had been filled a new gun pops up on the scene, the Glock, that's right, just as all these contracts had been mostly signed and both law enforcement and the civilian market got all thrilled with their lovely "Wonder Nines", the plastic fantastic came into being. It took a good long time for most people to warm up to these invaders from space but it did start the beginning of the end of the wonder nine euphoria.
....and here we sit today.
Now to my answer to the OP, most of the P series guns were fine pistols and a pleasure to own. They really were reliable as a stone, I owned an early model P85, I was in the Army so shelling out cash for a new gun meant I must have liked it plenty. The accuracy aspect became an issue for me as time went by, I could shoot other guns so much better than the P85 after a time, it really was what Rev says, I learned to "outshoot" that gun, it wasn't by a little, it was by a lot and it seemed every week the gap got wider between my newer better shooting pistols and my beloved P85, some years later I gave that gun to my nephew, he still has it. So as far as my only gripe about a P series gun that I actually owned it was that.
I could pick apart some design aspects about the metal framed P series guns but overall I find them a nice gun and they always bring back memories that make me smile.
One example and this is not really a design issue, I don't know how many metal framed P series guns I've picked up to check out just to find that some nitwit thought that rough surface on the frame rails was the reason they can't shoot a gun worth a crap or was the reason for it not working right. So they would take their frame and with some form of tool they should have not been allowed to get within 10 miles of, removed the rail hardening diamond coating that Ruger put on there for a reason with that exact rough profile.
The people that remove this coating from their, or god forbid, their buddy's gun should be beaten with a stick constantly and be forced to get a Jennings J-22 to shoot 2 rounds in a row for the rest of their rotten, stinkin' lives.
I will only say this about any and all plastic framed P series gun, I hate every one of them and always will and you can cry and call me poopie face or head for that matter, put a flippin' one eyed evil hillbilly hex on me but those guns suck, all of them.