Every positive thing you've heard about this game is probably true. It's fun, addictive and hard as hell. I'll never be one of those who can do a no hit-run on 5BC, but that shouldn't discourage you from trying this game. Especially since they've included custom and assist mode, which let's you experience the whole game and tailor the difficulty precisely to your level.
The DLC's are also higly recommended.

Given the gameplay loop I don't think Dead Cells is a game you "finish" on a set date, because it's very easy to make another run if you have some minutes to spare.