That's always a good piece of advice, but if you don't want to go through the hassle of setting your phone back up from a complete factory reset, you could also try a cache partition wipe instead, which won't erase personal data: Reset: Samsung Galaxy Note II | T-Mobile Support
What kind of problems are we talking about? The only out of the ordinary thing I've seen is that the radio seems dodgy -- one bar where I had 3, calls breaking up, etc. I'm not sure what would cure that.