I don't know too much about the "QA" models, but I have an "AS" ("Anti-Stress", the name they use for the SA/DA model) in 9mm and I find it to be similar in accuracy to the HK USP and the SIG 226. I find it to be more accurate than a Glock-type gun or a DAO gun though. I would probably say it is a little less accurate than the HK or the SIG for two reasons though:
(1) Because it is striker fired, rather than hammer fired, the trigger doesn't move backwards when the gun is cocked (like it does on every hammer fired SA/DA gun). In SA mode, the trigger starts from the DA position and just has minimal to no resistance until your finger moves it back into the SA postion. You get used to this as you shoot the gun more but it is a bit weird at first, and frankly it is an inferior system to the HK or the SIG. The benefit is that with a striker fired gun you can have a lot lower bore axis and the benefits that come with that, but you give up something on the trigger by doing so. I find that the take-up on the trigger either slows down your shooting, or decreases your accuracy. Others may have different experiences though. I find that if I slow-fire this gun, I can get some very good accuracy out of it though, and "acceptable" on rapid fire. too much thinking about "take-up" though when shooting fast.
(2) The frame of the gun is very very light. I don't know the exact measurements, but it's lighter than a Glock and way lighter than anything with an alloy frame or metal inserts in it. The slide assembly on the other hand is quite heavy. I believe that this combination is what causes the greater than normal "snap" this gun has, even in 9mm. Felt recoil is actually pretty heavy for a 9mm, I find. Definitely heavier felt recoil than a Glock 17. I think this "snap" decreases accuracy somewhat, especially on follow-up shots.
If you shoot this gun alot, you can overcome these "issues", if you find them to be issues at all. The P99 has a lot of nice features to it. The grip is the absolute best feeling grip of any pistol I have held. The interchangeable front sites is also a great idea that I wish every pistol had. You can pretty much dial your gun in for your shooting style in 2 minutes. The loaded chamber indicator, cocking indicator, decocker button, and interchangable backstraps are all good features too.
On the reliability thing... forget about that. These guns are easily the equal of all the competitors in that category. I don't know where that got started, but I agree with the above poster that it couldn't have started with people that actually shoot this gun a lot. I never had the slightest problem with mine, and I've shot it a ton.
I like the gun. It's not everyone's cup of tea, but I wouldn't hesitate to recommend it to anyone.