Metroid Prime 3: CorruptionTHE GOOD: -Improved Controls -Graphics -Easier back tracking -Combat more enjoyable then previous MPs -Worlds full of life and look good unlike MP2s darkworld
THE BAD: -Hint System as annoying and doesn't always tell you exactly which place you need to go -Voucher System if you don't have many MP3 friends -Some Boss fights are a little more confusing then previous MPs not in difficulty just finding what to do
SUMMARY: (Minor Gameplay spoilers)
Metriod Prime 3 is easily the best MP to date because of how much they've improved on everything. As the Wii controller makes combat feel like you're actually shooting them instead of the lock on system. Though you can still use that old system if you feel like it. These things must be changed in options first. You can also fight quite well without locking on to enemies which doesn't seem like much but if you've played an MP before you'll know that you couldn't before. This also helps looking around and exploring. Often to open doors and activate switches you must use your Wii mote to use them. While it might take a while to get used to it isn't annoying and immerses you into the game. Other touches such as being able to see Samus' eyes in the visor as she starts to Corrupt over the game only add to the experience.
Fans of MP and any Nintendo game will be surprised to know that there is voice over in the game. Which serves to flesh out the GF forces as they will be helping you through the game with information and later with actual help.
The power ups in the games are for the most part very cool in both puzzles and fights. They've also made it so the beams stack so you no longer have to switch between beams in order to burn or freeze. The freeze powerup was added to missiles so you won't unfreeze when freezing. Your ship also plays a much more active role and is able to perform bombing runs to destroy obstacles or help clear certain rooms, lift objects and act as a save spot.
Morphball was also improved upon as doing a double jump while in morphball is much easier. As you can now jump on your own using the Wii mote so you can simply jump, lay the bomb and then jump again. You can also do a boost jump, which while has no use is a fun thing to do.
The newest thing for MP3 is Hypermode which allows you to become extremely powerful for a limited time and shots. However you lose health for each shot you take and if you stay in Hypermode too long you will become corrupted. Hypermode can be both good and bad for the game, when you learn how to use Hypermode effectively (partial charge kills most enemies) it kind of makes the game too easy in some parts. However the game expects you to use it and not using it makes the game quite hellish.
Overall you should buy it if you have a Wii period. The only reason you shouldn't is if you think the game is too hard for you. As it's one of the best adventure games for the Wii if not the best (yes better then Twilight).