I had a 329 NG (.44 mag) and experienced numerous failures to fire. This seems to be a common problem with the NG series...apparently the firing pin is the issue (too short.) S&W will replace it, under warranty. There are enough reports of this problem that I would think S&W would do a recall, and fix the production going forward...or is that too much to expect?
In my case, though, my dealer took the gun back in trade and gave me what I paid for it...which I thought was decent of him. I ended up buying a new 686 and a new 642 (I had to kick in some cash.) I don't think I want another NG...although it looked great and felt great, it just didn't go bang.
Edited to add: not trying to be a smart aleck, but shouldn't this go in the revolvers category? Might get more responses there.