I post over at the XT225.com board, so I shouldn't repeat myself here. Mine gets about 80mpg right now and I'm 6'3, 280#.
Great lil' bike. Easy to maintain and reliable. IMO too cheap to waste money turning it into a dirt screamer, just go buy a YZF, Husky, whatever.
Mine is used a lot for errands and trail riding.
...Nowhere to go, and all day to get there...