Definitely overrated - he got lucky in all those wins.
Seriously, though, I hope this'll translate into a consistent 2006 for him. It's nice seeing the younger (in tennis terms) players doing well. Of course, Ljubicic performed very well, too, and overall, he was definitely the best indoor player of the year (and there's still Shanghai and Davis Cup left to see). Now he needs to translate his success into the Grand Slams, and we should have a very good 2006 for him.
EDIT: And that five set record seems very strong, too. Somewhat like Safin's record in them; it doesn't make very much sense, considering that neither one is considered the best 'mentally' (of course, Safin is probably worse in that regard) .