As far as previous versions, there's not much out there, besides the "ATV vs MX" series...which I never really liked.
Other than that, Supercross Circuit for PlayStation 1 back in 2001 was the best dirt bike game I myself ever played...as you could build your own tracks.
You can build your tracks in this one too, I just haven't gotten that far into it yet.
It's the graphics that're just the best I've seen yet out of any dirt bike game....any better, and you would actually be a live person...it's incredible.
The bikes aren't too hard to control....by the time I was finished with the 1st race, I was getting the hang of it...but I was already way back in the pack to make up any positions. Plus I haven't gone into the "bike set-up" yet either....I figured I'd just go with the settings it was at...and you can change many things!
I was also told that 2T's would be available in this too, though I have yet to come across any...but, I may need to play for awhile, and "unlock" them....we'll see.