How effective and accurate is Windows 7 system restore?

I have been using Acronis TrueImage for years. Just recently though I’ve just upgraded to their latest version 2011 with which I’m having serious problems. It renders the sofware absolutely useless. I have gone through their tech support and online forums without any luck yet. Since I can no longer count on this software I must start using Windows System Restore. How useful is it? Does it compare with using TI or similar imaging software? Can I totally rely on it to restore my system after a virus infection or registry screw up?