I picked it up for $20 and I don't feel like I wasted my money- I've actually enjoyed it quite a bit (I've only played the story mode, and I haven't touched multiplayer). The story runs a little on the cliche side and the voice acting runs from good to simply okay- but honestly, I've found it all to be quite fun.
Gameplay is a bit slower paced than most 3rd person shooter games, but that's to be expected from a game where you pilot a giant robot, I'd figure. The on-foot portions are a hoot, too. I'd say pick it up if you are interested, and just try to buy it for as cheap as you can.
"I am the rocks of the eternal shore...crash against me and be BROKEN!" -Apocalypse, X-Men:TAS