Couldn't possibly disagree with you more. It's one of the best games in the series, and I've played every Metroid title that exists. It's a bit different, and it may not fit your personal preferences, but that doesn't make it bad. It's an excellent and finely balanced game that I enjoyed from start to finish with the single exception of some frustration with the last boss due to a lack of information. That sucked and was kind of a letdown. Well, and I can agree that the final key hunt was lame. That dragged on just a bit too long. Otherwise, I love the game, and I'm friends with several other hardcore fans who also feel it's one of the best.
Anyway, the boost boss really isn't that difficult once you get the hang of it, unless you're playing in hard mode of course. Basically you just need to nail him as much as possible when he's in his regular Ing form, then when he goes into boost form, roll up into a ball and avoid him as best you can. Some have told me they had better luck staying on their feet, so that may work for you... but in either case just avoid him as best you can. If you get him to boost into the pillars, those'll drop the full 100 energy charges which come in real handy (if you're smart, you'll use all 4 throughout the fight, plus whatever you get from killing the random enemy spawns). Then when he goes back to his flat shadowy/liquidy/whatever form, drop bombs on him until he gets pissed and takes regular Ing form again. Then get up, blast at him again, and repeat until he's dead. Kill the other random spawns as necessary, either with bombs or regular shots. There's enough "downtime" to kill those when you're just busy avoiding the boss and can't damage him, so don't waste too much time on them while he's is in a form you can damage.