The P7 PSP is one of several pistols developed in response to a functional specification let by the German state police in the 1970s as they sought to modernize their equipment in the wake of the Munich Massacre. Several manufacturers produced pistols that met the spec in different ways. German police organizations were free to choose from the results. Instantly ready with no switches, instantly safe when dropped, totally reliable, and possessing some of the best ergonomics of any pistol every made, the H&K P7 met the sensible specification with a collection of clever design elements.
I took a P7 PSP on my first trip to Jeff Cooper's Gunsite for API-250 Basic Pistol in 1986. I got ribbed for bringing a staple gun to a shooting school. I got ribbed - "Hey, where's the rest of your holster?" - for carrying it in in a very minimal Rogers holster; a hand-signed early laminate job not much larger than a pager, a surprisingly secure speed rig, of which I've never seen another example. The Old Man said, "That's a fine pistol; too bad it's chambered for the wrong cartridge."
The P7 takes much less force to hold at full cock than it does to cock it. Anyone who can't cock a P7 is likely going to have trouble racking a slide or squeezing off a double action trigger. It is not noisy when cocking but it does make a distinct "clack!" when you release the cocker (unless you have the time, presence of mine, and fine motor skills under stress to do the silent decocking trick).
My P7 is utterly reliable. It never once failed to feed, fire, extract, or eject all week, unlike most of the 1911's I've shot or seen shot. During the failure drills rangemaster Louis Awerbuck told me "the P7 doesn't stop, but you need to play along." In my direct experience the only other pistol that comes close to this level of reliability are the various Glocks.
It's fast. I wasn't often the first from the holster, but I was always the first one done. It was Wednesday before I realized I was shooting "hammers" back to 10 meters. The magazine change is faster than it looks as it does not share the usual disadvantages of a heel mounted magazine release. Press the P7's latch and the magazine fairly springs from gun, if you aren't already removing the magazine as your hand sweeps down on the way to your mag pouch. It's sights are fairly coarse which contributes to speed at 25 meters or less.
I used more ammo than most making the hard set poppers fall over in the outdoor simulators - "Better switch to the head," and shot halfway through the shoot-off (there were only two other minor calibers s in the class). I was looking forward to the .45 ACP version, but the prototypes circulating through various law enforcement agencies at the time did not deliver on the promise. The few shooters I spoke with who got to try the 45 ACP version admired everything about it except it's reliability - seems the 45 ACP pressure curve was all wrong for the gas-retarded action. That's probably for the best as I'd have only "needed" one pistol if there was a P7 .45 ACP in the world.
The PSP had a few flaws. The slide serrations tended to rub a fella's strong hand thumb to the pink. A touch with a fine file can fix that. The squared trigger guard slowed my presentation so I had the Gunsite 'Smithy round it off for me.
The trigger on my P7 is not as nice as that on a 1911 when being used for precise work at a long range. The "sear" feels like it's rolling off its engagement, which combined with PSP's coarse sights, makes deliberate work on the 50 yard line pretty challenging.
The P7 PSP could certainly heat up to the point of discomfort if shot a lot. This is a problem only on the training range. I read one Usenet anecdote of a cartridge "cooking off" in an overheated P7 but have never seen another.
You can't use lead in the P7 or it will gunk up the gas system. Big deal, only junky gun range 9mm ammo comes with lead bullets. At least the P7 won't go "KaBoom!" like a Glock does when fed a steady diet of cheap remanufactured lead bullet ammo. It only eats jacketed ammo of high quality, but who would anyone fight with anything less?
Being all steel, except for its synthetic grip panels, the P7 is heavy for its size. These days single stack 9mm pistols weigh half as much. Still, none of them combine as many nifty design elements in one handy gat.
The later P7M8 and M13 were less comfortable in my hand and the sharp little magazine release flippers were not nearly so fast as the heel latch on the PSP. The heat shield on these later models were a nice addition at the range, but even at Gunsite my PSP rarely got so warm I was uncomfortable. The 380/22 convertible was interesting but not that much smaller or lighter than the 9x19 and it was bloody expensive. The P7 M13 "Gordo" and the P7 .40 "Orca" (my nicknames for them, not the factory's) were bulky and abominably top heavy, respectively.
The P7 was a certainly a poor choice for cops transitioning from DA revolvers to self-loading pistols. Many many cops, rangemasters, and administrators learned the hard way that the boys in blue had been drawing their revolvers with their fingers on their triggers all these years.
My experience with the P7 was that that it's manual of arms made it a good choice for the one gun man (or woman) who is inclined to undertake serious professional instruction. Its price put it out of reach of all but the most serious pistolero. The average cop has proven much happier with DAO self-loaders in 9x19 or .40 S&W. Serious special weapons types and other operators seem still to call on a tricked out 1911 in .45 ACP when it comes time for precision in a hurry. Unless the GSG9 is still using their dream gun it seem the time of the P7 has come and gone.
Still, I guess I like mine.