It's alright, but slightly flawed.
The story is basically that you, Samus, have gotten a telepathic message that tells you to go to the Amblic system to seek some sort of 'Ultimate Power'. To access this power, you need to collect these weird diamond shaped thingies called 'octoliths'. To get an octolith, you must collect three Amblic Artifacts. After you get three Amblic Artifacts, you step into this portal and face a boss. There are also six other hunters trying to collect the octoliths, so you have to fight them.
This does get somewhat repetitive at times. Collect three artifacts, go to portal, kill strange giant weirdo. Repeat.
The graphics on this game are decent, if a little screwy at times. The environments look great, but sometimes they do slow down at times when there is a lot of action going on. The pre-rendered cutscenes are gorgeous.
The controls are good. At first you might be moving around the place as if Samus is drunk, but you'll eventually notice that the controls are similar to a PC FPS. The d-pad and r-trigger are like the keyboard, and the touchscreen acts like a mouse.
The multiplayer aspect of the game is one of my favourite parts of the game. You can play with up to four players, online and local. There are heaps of modes to play, seven to be exact. These multiplayer modes include nodes, battle, prime hunter, and some other ones. There are about 25 multiplayer maps to play on. If only one player has the game, and the rest use DS download play, you can only play battle mode and everyone except you has to play as Samus. There have been some complaints about alt-spamming (overusing your alt form), and most people consider it a cheap tactic.
In conclusion, Metroid Prime: Hunters is a good, but somewhat flawed game.