Excellent accuracy...can tag players through holes in spools, etc. Can get really quick ROF, especially using .45 frame. Trigger pull is very short. Light weight, small size, excellent design and layout. As close to the perfect non-electro as you can get. Also, it's actually quite easy to work on/with if you are even modestly mechanically inclined.
Not much...the bolt knob has been known to break at the threads (happened once to me, a couple of times to a friend), but it's traceable to using non-Palmer barrels like the Autospirit (because the bolt enters the barrel; tightbore barrels have less room and create stresses on the bolt pin). There's not a lot of people who can work on the gun, just because the guns are relatively rare and trouble-free, and people think PPS won't work on a gun that someone else has worked on. Not true. They just won't fix someone else's screw-up for free.
The only other thing is that some players can't seem to get the hang of the trigger, especially players used to electros.
I'd stack my Blazer up against anything. It's got the speed, accuracy, ease of use and comfort level to excel in any situation for less than most custom Cockers (Freeflows and Shocktechs). With only a .45 frame upgrade and a Stabilizer, you get a trigger throw that's about the same as a stock Angel and the best all-around reg on the market. The Blazer runs well on either CO2 or HPA, and you can get one with the .45 frame, Stabilizer, and a vented barrel for under $650.