Underrated is right, ZX Advent rocks.
The story, not gonna lie, I didn't care, I did love seeing the animated cutscenes however, and I'm glad they made an extra effort, instead of plain still images with text. Music is great, it's a Mega Man game after all, though the classic NES tunes are very close to my heart and the music here is not up to those in terms of being catchy and just plain charming. Gameplay, despite the open world, is quintessential Mega Man 2D action, yes there are more weapons, yes there is more focus on story, but when you run around, charging your buster, blasting enemies and battling bosses, it took me back to what I loved about the series and video games in general. I sound like a broken record, but be warned, do not complain about the difficulty, it IS a Mega Man game, what do you expect? Besides, there's a "Beginner Mode" which is very generous and easy. I did fine in the game, no majorly, pull your hair out frustrating moments, until the final boss, that's a tough one to say the least. But what a rush when I beat him, one hit and I would've been dead and he started one of his near-impossible to dodge attacks and I manages to blast him just a second before he hit me. The game is also longer than the average MM game.
Mega Man ZX Advent is an underrated game in the series, furthermore it rekindled my interest in video games, now I'm compelled to play the Zero games and the previous ZX game. I wish they could make more 2D MM games, instead of those Battle Network type RPG games.