The boss battles are pretty hard - I perished a ton of times on almost all of them. But there are always checkpoints nearby, so the penalty for losing is low. (Really it's just time on the clock, if you're interested in speed running.) One of the help text thingies they show you while loading says that "no attack is unavoidable", and that's true - once you know what you need to do, even the hardest battles become reasonable. And one of them is pure joy.
I do miss the music of Super Metroid. Dread's music is fine, but none of it is memorable, and it doesn't lend the same kind of character to the different areas that Super Metroid (or even Zero Mission) had.
As for plot, that is also fine, and I can't say much without spoiling things, but I will say that they didn't include much detail, and I don't feel like this works as the "ending" of the side-view Metroid story, like the pre-release media paints it as. At the start we don't find out how the Federation reacted to Samus's rebellion in the previous game, or where the Dachoras and Etecoons went, or why Samus's armor looks totally different now. And while the ending is certainly more plot-heavy, it still raises a lot of questions.
But anyway, I'm very happy that they finally made a new Metroid game. Hopefully it will do well and they'll keep cranking them out.