I've been using it and its predeccessor (version 2.7) since October 2004, and haven't had any problems or dramas. That could be as much to do with my cautious approach to surfing and the fact that I don't do any 'high risk' stuff such as file sharing or hanging about at 'social' sites and, of course, to not using IE!
No software is foolproof and I have seen some allegations that NOD has 'missed' some exploits but I imagine that all AV's have done that at some time.
NOD does have one odd quirk, namely that the icon occasionally fails to show up in the systray. This happened with 2.7 and now with 3.0. There were threads about it at the NOD section over at Wilder's Security Forum and a 'cure' may have been suggested. I haven't looked too hard because I allow the splash screen to load at bootup so I know it's working and I get the Update confirmation messages each time one is downloaded.
You can elect to receive an email notification of updates (if you want them), by registering here;
https://secure.eset.co.uk/forms/threatalerts.asp Also, in case you want to see what other users are enquiring (or complaining) about, here is a link to Wilder's;
http://www.wilderssecurity.com/forumdisplay.php?f=88 Don't be too put off though, remember that people without problems (like me) don't post to say how happy they are with the program!.
Login 
General Security 
