The main hook of this game is the wifi coop multiplayer for up to 4 players. You can play through the entire story mode with people from around the world. It's really fun and awesome IMO. Vistabuser and I played through the majority of the Japan game and we had a blast. It's addictive as crack sometimes. Too bad it tended to lag VERY badly for us sometimes. Maybe they'll fix the lag in the US release.
Sadly, the single player mode just isn't as fun. Ring of Fates was probably a little superior. Despite having pretty cheesy dialog and voice acting, the story was actually kind of in depth and sometimes engaging. Not so much with Echoes as it's more generic. I don't think your character talks much or at all and your wifi or AI partner NEVER speaks or is featured in the story.
I'd give this game a 7/10 if you play it in single player or a 9/10 if you play with a friend. I'm biased in favor of the multiplayer, and would normally never give a game 2 different scores when comparing single or multiplayer, but here, it matters. If you have friends either locally, or anywhere in the world with this game, I can highly recommend this game. If not, your mileage will vary to the point of either like or hate. Few things are as fun as trudging through locations cooperatively and helping each other solve ingenious puzzles or platforming. But it's pretty dull when you're playing alone.
Also, you can hit each other in the game. That can actually be kind of fun to mess with each other.