That image is quite the stretch (and I would know that because I sometimes experience that problem too)
Anyway, I'm not sure if this is your first hack (judging this was your first post), but without constructive criticism, this doesn't look relatively bad for a first hack.
Trust me, my first hack had all of the things that you shouldn't have in a SMW hack (i.e graphical glitches, goal traps, spammed cement blocks, stacking munchers, etc.)
I just wished I still had it today
As for suggestions, replace those cement blocks with grassland tiles. In my opinion, cement blocks should only be used as much as
question blocks or in
1 x 1 tile spaces (i.e. 1-wide walls or 1-height ground).
Also, you shouldn't place two Banzai Bills that close together since Mario and other sprites may turn invisible. If you're using SA-1, you should try without it so you don't abuse the amount of sprites you put in a level.
Overall, you're doing pretty good, just keep at it!

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