I had an earlier P99, chambered in .40 with the green polymer frame. For some reason, I had fits with disassembly and re-assembly of it (didn;t dig that big plastic takedown piece) , and i practically hated that thing, and I sold it.
Years later, I traded a G26 for the newer P99AS from a guy that wanted something smaller and more concealable, and I love this pistol.
It's very accurate, and has been 100% reliable with everything from Federal aluminum, to Russian steel cased Tula, to various others ammos.
I also like the big,wide sights much better than the little micro dots so many pistols seem to have (Beretta 92,CZ75,etc).
It obviously doesn't have a target-quality trigger, but it's a combat/SD weapon, so it isn't necessarilly supoosed to, and it is still better than a stock Glock trigger, and I think it's plenty decent enough.
A big selling point for me is the decocker, which I've always thought were a great idea. Also, I shoot this thing as good (actually,better)in double-action as i do in single action (oddly, that's the case with a lot of pistols for me, I don't know why, seems counter-intuitive to me).
Another plus is that Walther is using the tenifer surface treatment on the slide, which Glock has stopped using in favor of some thin,easlily worn, rust-magnet stuff.
Some folks don't dig the paddle mag release, but I like it fine, and unlike some people worry about, I have suffered no life-threatning confusion switching between that and other more common systems
.
These are excellent pistols, and the overwhelming majority of reviews concur.