You know the proverb : Easy to learn, Hard to master ; this is one of those.
Gorgeous little game (not actually small neither short), Deep and dark story (quite literally), one of the best OSTs I've ever heard (if not The best one), nothing revolutionary in the gameplay but masters the genre (the controls are soooo smooth and responsive, like an old-school game on a CRT tv) : I recommend the game to basically anyone with a controller (and get one if you don't, it's worth it).
But do not let Hollownest (The region in which the story occurs) beauty fool you, this game is hard. But fair. (But HARD.)
Anyway.

TL;DR : Beautiful, hand-drawn game with good music, great gameplay, AND an actual plot. It is challenging, doesn't hold you hand, but is really fair even for beginners, especially gamers who would like to give a chance to the genre.

(PS : I didn't say Metroidvania, nor did I compared it to Dark Souls, but even if game devs say otherwise, there's a part of both in Hollow Knight)