I finished Metroid Prime! It came out a good year or two ago. I didn't buy it until a while afterwards when the price had come down to £20, and then procrastinated over playing it for many more months because I was at college with a small, squinty television on which the graphics were difficult to make out, and also because basically I didn't feel like it. I picked it up again just a week ago and started playing again. Verdict? 9.55/10. Awesome, awesome game. Not a first-person shooter in the traditional sense - targeting things is a skill-less matter of holding the L lock button down, with the controls given over more to platform adventuring and exploration. It feels more like The Legend Of Zelda: Ocarina Of Time than GoldenEye. A large number of carefully-spaced power-ups provide new toys to play with, each placed just as the most recent one becomes dull. Weaponry is varied enough to make figuring out optimal takedown strategies for each of the many, many varieties of enemies a pleasant task. Exploration is always, ALWAYS rewarded with missile expansions or other worthwhile power-ups. Puzzles are logical and cool. Graphically it is a dream throughout. And the Morph Ball mode? Gorgeous.
Metroid Prime is an excellent game. I got about 25 hours of entertainment out of it altogether, that's two completions - first with no guide, and second on Hard mode with 100%, to unlock all the unlockables. Both were pretty tough challenges, especially the bosses. The save point system is unforgiving but definitely fair. This results in some difficult sections. You can't clear out an area permanently; enemies respawn (often in greater numbers). So you end up with several BIG sections THRONGING with bad guys lying between two save points, with no choice but to fight your way ALL the way through in one go. Difficulty is high to start with but once you figure out your strategies for beating each enemy efficiently you'll be surprised how easy these things become. Also, the bosses - initially complete nightmares, but again, a moment of thought and a little practice will see them all falling. It just takes dedication. And you WILL be rewarded. Relax, Ikaruga and Super Monkey Ball are MUCH harder.
Overall I have only a tiny quantity of complaints - no replay value after you beat it 100%, for one thing, and the final boss... well, let's just say I wasn't particularly intimidated. It doesn't quite live up to its (awesome) concept art (four galleries of production images are your reward for various achievements). Lack of a multiplayer mode doesn't worry me too much although in any case this is promised to appear in Metroid Prime 2: Echoes, due to be released in November. (Side note: friend of mine has been using the internet screen name "Echoes" for something like four years now. Lucky devil.)
In conclusion, Metroid Prime is a technically flawless and absolutely awesome solo adventure. Buy it, love it, await the sequel.