I've been playing TMN for a week now. I really like this game.
1.) It's free
2.) I love editors (TMN has a fairly decent one)
3.) Did I mention it's free?
I'm probably going to upgrade to TM United which is the full retail version of the game. Only because I want to get new car, more environments and the ability to use "user created" stuff.
lol, I used to have a few slot cars and this reminds me a lot of slot cars, so it's pretty sweet. It's worth the 500MEG+ download.