[Easy]
Use more new combos.
00:22:162 (7) - Unnecessarily clunky slidershape. Use a normal curve.
00:24:530 (8,1,2) - Inconsistent spacing.
00:37:951 (1) - Blanket the previous (8) better.
00:44:267 (5) - The second red point is too early to hit the synth note. Move it just a little bit upwards and right.
00:47:425 (7) - This also doesn't follow the music perfectly.
00:54:925 (4,1) - Doesn't work. Plays really clumsily, looks even more clumsy.
01:01:241 (4) - Center the second curve - make it like the first curve.
01:03:214 (1) - Starting from here, don't leave such long sections unmapped. Fill in some hitobjects. Long breaks are so 2008.
01:06:372 (2) - Another unnecessarily clunky slidershape.
01:09:530 (4) - Move the middle point just a single square upwards.
01:31:635 (3) - Use additional curves to make it look not so boring.
01:36:372 (6,7) - Would be better if these were identical.
01:39:530 (8) - The red point isn't perfectly centered.
01:42:688 (2) - Same as above, though not as big issue.
01:47:425 (5) - Again, make it more interesting. Apply curves or use imagination.
02:19:004 (1) - The red point doesn't follow anything in the music.
02:22:162 (2) - Same as above.
02:25:320 (3) - Aaaand same as above.
[Normal]
00:15:846 (1) - Delete the unnecessary red slider point.
00:19:399 (2,3,4) - Should be identical and blanketing each other.
00:26:899 (3) - Should be blanketed by the previous (2) more properly.
00:28:478 (1) - Move this up-right for better flow.
00:38:741 (3,4) - Should be blanketing each other.
00:44:662 (4,5,6) - Whelp, looks and plays bad. Use better slider designs and use a flow that is fun.
00:49:004 (6) - Should be blanketing the next (7).
00:50:583 (1) - Again, don't leave big sections unmapped. That stuff starts here again.
The first entire part of the Kiai uses really bad flow and slider shapes, and to avoid pointing out every detail that's wrong, I'll just leave it at "consider remapping the first section of the Kiai time."
01:46:635 (6) - Could be blanketing the next (1).
02:17:030 (2,1) - Really highly obscuring overlap. Absolutely not allowed.
[Hard]
Assuming you're looking for a GD and deleting this, leaving this unmodded.
[Insane]
I'm not exactly sure about the flow here. Doesn't seem fun for me, honestly.
00:15:057 (1,2,3,4) - I'm not sure if this manual stack is really suitable. Doesn't give exciting gameplay.
00:27:885 (1) - Too close to the previous object, especially as the previous beat was left unmapped. You should really add a circle there, and fix the spacing here. It's really a confusing combination.
00:37:951 (1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8) - The repetition is boring and looks bland with this straight slider pattern, too.
00:50:583 (1) - The slider shapes starting from here are really bad, also the long breaks start from here again that you should map properly.
01:19:004 (1,2,3,4,5,6,7) - Bad overlaps and odd flow. Consider just making something more usually accepted here.
01:22:162 (1,2,3,4,5,6,7,8) - Boring, overly easy pattern. Sure, I get the design, but you can design a similar patter well using proper distance, too.
And in the end, use more normal slider shapes again, and don't abuse new combos.
Easy and Normal might be just fine after several mods, but I'm suggesting to find someone to map an Insane GD, too. Would be a better and more easily rankable mapset that way. Sorry if I sound harsh, but I'm trying to be honest and helpful. The song is fun and think music like this deserves to be ranked, too. Good luck!