your hack does not necessarily look bad in any way. however, i do want to point out a couple of stuff:
the overworld looks rather empty and has perspective errors, but i know you're still working on it. the level design could use work: most sections look empty, lack enemies, etc. i suggest playing some hacks here for inspiration on level design. anyways, specific questions include:
is mario riding yoshi here? i thought he is usually seen at the ending fade-out?
are these custom map16 blocks? i recommend using custom blocks and reading tutorials on the "tutorials" forum for how to use custom blocks.
what's the purpose of that blue vertical line in the background?
"havn't" should be "haven't".
i hope you can fix these issues, and i wish you luck with this hack!
--------------------Currently: Starting college!