Can't speak to the 992, but I have had a 990 with a 4" barrel fror a couple of years. Well over 1000 rounds through it. It had to go to Taurus almost immediately because the cylinder would lock up after about 2 cylinders (insufficient cylinder gap). No problems since, but it lacks fit and finish. The star wheel looks like it was chewed into existance by a pack of angry rats. But, it is actually really accurate, suprisingly so. I shoot it more than anything else I own. A .22 DA revolver is a blast to shoot!
That said, given the affection I have developed for .22 DA revolvers, I am definitely in the market for something nicer. I would buy a .22 built on the Ruger GP frame in a heartbeat, but since that doesn't exist I am probably going to end up getting either a S&W 617, or an earlier K-22 or model 17 if I can find one (a diamondback would be my grail gun...) Anyway, for me, the 990 has been very worth owning, and quite accurate, but could be a lot nicer. They are a good value if you get a good one, but definitely a case of getting what you pay for. Since QC at Taurus seems to be lacking, be sure to inspect the one you are purchasing carefully, and don't hesitate to reject a substandard example, you will be doing yourself a favor.