Yeah, it's pretty good.
MP3 had the best controls for an fps I've ever played (even though it wasn't exactly of the fps genre,) and they basically just put them onto the prime 1 and 2 games. They're still damn near perfect; I haven't run into any motion interaction yet (in prime 1 and 2) such as the door commands and welding and such from prime 3, but honestly I don't miss them. The laser precise aiming is more than enough to breathe new life into an already fantastic game. I suppose the difficulty might be lower on an absolute scale, but if the difficulty is reduced due to improving the controls, does it really matter; no, it does not, because difficulty due to control issues is fake difficulty, and no one should mourn it when it is expunged. In any case, you have normal and veteran, and I'm assuming an expert after you beat the game, as in prime 3, so there's always that.
The packaging is quite fleshed out. You can just play a new game from each of the games and can work on them in any order you want, switching from one to another through the menu with no obligation to finish the current game. The mp2 multiplayer is there also (if anyone actually cared about it, worry not, for it is still there for you) and it brings in the token system introduced in 3 to unlock extra crap, including the soundtracks. Now, since the mp3 game itself didn't have the rundas fight song, I'm assuming that this one also doesn't, so that sucks, but aside from music, there is concept art and little add-ons like that that you can unlock with points. You can also buy the fusion suit that was availible on the gcn prime 1 through gba link, just for completions' sake I guess.
It's also just 50 dollars, and it comes in a nice metal box.
If you're struggling to find something to justify your wii until the twilight princess sequel, try the prime trilogy. If you've played them all already, and really just can't bring yourself to play a metroid game more than once, then I don't know why you played it in the first place () but also, you could skip it. For anyone else, look into it.