Yeah, Prime ain't all that hard...though I found excaping from the Space Station on Hard Mode a tad difficult if you aren't careful- like 6 shots from a Pirate will do you in...QUICKLY.
For Metroid Prime, I've found that you can take little or no damage in the first form by morphballing up under him quickly the first time it "neighs" (when MP lets out half of some garbled scream before charging headfirst into you), and shooting every pair of tracked particles it projects. The charged power shots can always be space jumped/dashed away from, and contrary to popular belief, EVERY BEAM COMBO does loads more damage (even the flame thrower).
The Ice Beam in particular does the most in combo form- after laying a combo beam on MP in Ice color, it completely freezes him (like every other frost-capable object in the game) and ONE SINGULAR shot will send him reeling. I think RETRO compensated for this weakness by making it VERY hard to catch him in white color, combined with it only appearing after his second/third stage of attack, so you'll have to wait.
The second form (the actual fission Metroid form of Metroid Prime), was alot harder for me because of the randomly placed metroids spawned that get in the way of the boss while you're armed with the Super Metroid weapon.
One "glitch" I've found against this, per-se, is the rubble (remains of the Metroid Prime's outer shell) can be used as a platform of sorts. Once on a certain spot of the shell, the MP CANNOT (and I repeat), CANNOT hit you until you move to the edge of the body, or hit the floor again, nor can it spawn Metroids. You can pretty much get on the ground, tag MP with the Hyper, and jump back on the platform until it reappears or drops some Phazon again. This is a very slow process, but I've found it too work consistantly and I've beaten the game with 100% life this way dozens of times.

It even works in Hard Mode, which surprises me considering how stepped-up other enemies AI is...
But alas, that's my rant for the day. For the record, I died like 6 times trying to beat Thargos (or whatever the rock creature's name is) the same way I did in normal mode- needless to say it didn't work, and you'll need EVERY missle expansion and energy tank you can get your hands on before you face him.
To brag, the quickest time I've beat the game on hard mode is 3:36:12. Anybody get something quicker than this?
-Official Ninja of [coming soon]...