I've owned 5 TM's in the past, 125s and 250s 2strokes. All in all I've been happy about them. One of the nice stand-out issues on the 250/300's is the gearbox durability! they never fail, can't tell if it shifts worse or better than others, but they last very very good. So does the rest of the bike. The linkage bearing sealings is O-rings instead of seals, they let no dirt in at all!, nice. One thing you'll get to notice is the sealing of cylinder/pipe, it always leaks a little black trace running down the cases. But it's no big deal, just renew the O-rings often. They're nice bikes.
But I changed to Husky by the way, because I wanted a 4stroke (TC450), and I found the new 450 a good bike. So far It's very good!