I moved up from $2NL to $5NL not so long ago, and played really badly at first (was down 4 buyins after 4k hands, though did get a bit of bad luck in there too). Since I stopped being a retard, I've been beating it pretty easily, but I still don't find it as easy to beat as $2NL.

If I had to generalise I would say people are tighter preflop and looser post flop than at $2NL, which suggests it should be easier to beat, but I think the main difference is that at $2NL there were a lot more players thant REALLY sucked and would give you their whole stack really easily.

With respect to the comment about people who play for shits n giggles buying in at $5NL and not $2NL, I remeber at $2NL it wasn't too uncommon to see guys who just pushed every hand until they went bust or got bored (normally 10-20 hands ish), which was brilliant because lots of people at that level are scared to play for their stacks without a premium hand, however I very rarely see them at $5NL.