For me, Powered Up was a lot of great ideas but very badly presented. An arguably strong game made for a poor remake due to the radically altered character-to-screen-size ratio that left the game handling more like a GB title than an NES title. You'd think the "Classic mode" would be its saving grace, but that sadly isn't just Classic level design: It strips out all new features save visuals (and honestly, if you're not even including the new soundtrack, then why the hell wouldn't you just insert the NES rom and be done with it?). The game is also the textbook definition of poor difficulty balancing. There is a TREMENDOUS difficulty spike between Easy fortress levels and Normal fortress levels. The earlier pits you against enemies that barely put up a fight while the latter is the single most ball-breaking challenge to exist in all the franchise if your player is not named Proto Man. Fighting Yellow Devil in the game's claustrophobic screen size is bad enough, but 9 boss battles with no recovery is flat-out uncalled for.
More minor complaints include the boss weakness remixing, which I feel was a cheap and unnecessary curve ball. Again, this is a remake, not a World or Xtreme game. It's not borrowing from anything but MM1, why shouldn't MM1's weapons maintain their original strengths? And the art style shift was a radically extreme exaggeration of an old memory. Nobody honestly believes that's what Mega Man was supposed to originally look like. At best it's an amusing distraction before we return to our traditional views of the characters, and at worst it risks alienating the existing customers. Whoever thought Universe was a good way to "westernize" Mega Man really missed the lesson here.
Of course, being a bad remake doesn't necessarily make it a bad game, insane difficulty spikes and all. I loved the idea of a level creator and playable robot masters, with Proto Man and Roll joining in as well. But despite its potential, the end result of Powered Up was a considerably weak attempt at "modernizing" Mega Man that wound up competing with its original rather than complimenting it. Quite frankly, the fact that Inafune claims to not know why this game didn't sell worries me. Of course, the PSP's status at the time probably didn't help matters, and neither so did Capcom's uncharacteristically iron-grip attitude towards a hacked save file in the aftermath of the game's release.