This game is just plain awful. The only reason to buy it is to keep your X collection complete.
First the gameplay is just plain horrid. It starts out decent but then you are given the crappiest 3D camera ever. It's got clunky controls and you can't even move the camera. You get a lowsy auto-lock which really doesn't even work that much.
Sure they had some new additions. The only good one being you can switch characters on the fly. The also added Axl. Sorry to say it but he's basically a carbon copy of X but he can hover and rapid fire. That's about it.
Oh he does have this lousy "transform" ability but it's not even worth it. You have to deal the finishing blow with this really slow, really weak attack.
I suppose the graphics are decent. The FMV's look pretty good and the in-game graphics are withstandable. It's pretty average when it comes to the look.
As for sound. God it' s terrible. The music is decent. MMX and MM games typically have good music. However the voices are terrible. A couple of the actors give no emotion at all, not too mention how awful Axl sounds. And the bosses have the most annoying "catch-phrases" ever. I will never forget the repeated yelling of "BURN TO THE GROUND!" (honestly, he never stops).
As for replayability. Yeah there is none. And even if there was you wouldn't wanna play it again.
I should also mention it's fairly short. If you want you can easily beat it in a day although I don't understand wanting to play this game.
Seriously though, this is coming from a long time X fan. Just skip this game. You will do yourself a favor.