So I played through it. Still has blatant edits of YI 1 and 2. They're not even changed from the original version 1.0 except for the slightly longer Muncher pit in the second level. I felt like in level 1, that I did almost nothing but bullet hopping.
Here's why I don't like having to carry power-ups from level to level: it means that I am forced to play through another level just for a power-up so I can try the level I'm on again. Level 2 requires a mushroom from level 1, and there was one point where I screwed up a savestate on level 2, and since the mushroom in level 1 isn't until the very end, I have to play through level 1 again just to try level 2 again. At least level 1 wasn't hard at all.
The invisible coin-blocks aren't so much challenging as they are tedious. They are way overused, not even for puzzles.
I assume that one level was supposed to be a time challenge? Well, I got through it with 53 seconds remaining. It would still be possible with a mere 54 seconds, although if it's short enough for that, then it's probably too short.
The entire second room of the castle is just the unchanged wooden columns room from Iggy's castle in SMW. If we don't like blatant edits, what makes you think we will tolerate unchanged sublevels?
The last level had severe sprite lag in the part with the Lotuses and the Sumo Bros. Not only that, but spin jumping off of note blocks is not fun and very difficult to do in real time, harder than P-Switch jumping.
--------------------Legacy custom music
How am I so creative? I think taking walks might have something to do with it.
Every single level I will ever make in SMM2 will be easier than Ultra Necrozma.