Out of the box it's a bit cut down compared to the content in Trials Evo, but it has a lot of potential. Multiplayer took the biggest hit, you can no longer make/download custom Supercross tracks and there's no online multiplayer out of the box (it's coming soon in a patch).
Despite this it still has great Trials gameplay, the Extreme tracks are truly brutal and individual track objectives add some great replay value. Definitely worth picking up the retail version as it includes the season pass for a lower overall cost.