The 01 RM250, which I rode for a season, was a pretty decent bike, but did have a few trouble spots. The first of which, was the fork had some harshness, and required revalving to cure. After that, it worked well. The engine was a bit lack on low end power and top end overrev, but a set of Boyesen reeds and rejetting cleared most of that trouble. Others reported success with porting. Ergos were good or OK, depending on your preference. The stock bar is low for most people of average height, and the seat is a bit low, too. These troubles are easily cured with a taller bar, and the seat foam from a 01 RM125 transforms the RM to a nice roomy machine.
Lastly, the engine is sort of touchey about jetting, and will ping if jetted too close to the edge. Race gas at 50% is a good idea.
Mechanicaly, I had zero problems with the bike and it never even fouled a plug. Two thumbs up!! :)