Easily one of the best Metroidvanias (if not THE best) in recent memory. I was worried it wouldn't live up to the great WB/MW series, but it's just as good as the others, maybe even surpasses them in some ways (though I dunno, I've got a pretty big soft spot for Dragon's Trap/Curse). It's a pretty big game, too—something like 15–20 hours. Great music and graphics, and I'm surprised about the latter because I initially thought the sprites looked a little dumb, but the release version has improved greatly from early footage. Still not as pretty as Lizardcube's Dragon's Trap remake, but a very good effort.
This is the kind of expansive adventure I'd hoped Shantae: Half-Genie Hero would deliver on, but that fell a bit flat for me (good game regardless).
One last thing: Good God, if you play it, change the intro music to Japanese. Not because I'm a weeb (though I am), but because the default pop-punk song with shitty vocals is just atrocious. I guess people like it since it's featured in every YouTube video that talks about and praises the game, but after the first time seeing the animated intro, I was happy to see you could change the opening track to something less grating.