So I finally finished this a few days ago. I'm really happy I did, but I seriously don't get why everyone is going crazy for this game.
Yes, it's a fun, charming platformer. Sure, it uses the Vita features well. But to compare it Super Mario 64 is...Well, no - not even close (at least to me). Mario 64 was something totally special and unique - the exploration, the experience, the magic. I think the comparison between Mario 64 and Tearaway has a lot to do with your exposure and experience with Mario at the time of release.
Tearaway was a neat game, but it felt more like an old folktale. I'm not into folky stuff like that, so that definitely took away from the experience for me. I think everyone who owns a Vita should at least try the game out, but I wouldn't go in expecting the system savior like some have touted it to be. I guess I was expecting more of an open world experience. Many folks said to me, "Just wait until you get to that last third to pass judgement." And I did. I forced myself to finish the game to make sure I was confident in my opinion on the game.
I'd say it's a good 8.5/10 game. Fun for what it is, great for showcasing what the Vita can do, but not a defining moment in gaming [for me]. I think everyone will have their own experience with it, and I think that's what will make Tearaway special and memorable.