• Re-textured world maps
• All levels replaced
• Loads of creatively themed tilesets (designed by me!)
• A few new custom backgrounds (also designed by me!)
• Custom music from PMD Blue Rescue Team (if I ever succeed in putting it in)

http://www.mediafire.com/?fdnz8fab4ch49g2
(Special thanks to Deltier for fixing a bug in the patch, use NSMB Editor to apply patch)

Positives:
• The world map retextures were fantastic. I didn't even think it was possible to convert World 7 into a huge airship.
• Many levels had entirely unique themes, used hardly more than once. It takes a lot of dedication to implement an entire tileset just for a single level.
• The ghost house puzzles were very clever and perplexing. You should consider doing a puzzle-themed hack, it's clearly your specialty.
• I know you didn't make them entirely by yourself, but most of the backgrounds were beautiful, 7-1's background especially.
• World 8 was pretty awesome. The level design was a little better than the rest of the game and there weren't a load of cheap "fake difficulty" gimmicks like I usually encounter in late-game Mario hacks.

Negatives:
• World 6 was a huge disappointment. When I saw the star icon, I was pretty excited for a space world or possibly a bonus-style world. When I instead saw it was a second desert world, I wasn't happy about it. You missed a pretty big opportunity there.
• The sound hex is wrong in nearly every castle level. Silent Thwomps are very unprofessional.
• There are way too many blind jumps throughout the game. If you want your levels to include bottomless pits, make sure there isn't too much vertical scrolling.
• The fact that the game rewards you for playing on easy mode (Luigi) is a pretty huge flaw. Not being able to unlock all the star coins while playing as the clones only encourages people to play as Luigi and avoid the clone challenges entirely. It would have made a lot more sense to have those star coins inaccessible to Luigi and available to Clone Mario instead.

Positives:
• The graphics are out-right amazing. Many hacks attempt and fail to recreate a modern Mario feel, but this hack succeeds to capture the feel almost perfectly.
• The custom musics are very well implemented. No track is too loud or too quiet.
• Every level has a new challenge. It's very common in fanmade Mario levels to find a complete clutter of random challenges, but this hack spaces out the challenges level-to-level, which is very professional, much like official Nintendo levels.
• You may not have re-themed all the worlds, but nearly all the worlds you did re-theme were astonishingly creative.
• The FG effects (such as the falling leaves, the sandstorm, etc.) are very well done and unique.
• While it's unconventional in a Mario game, the Arceus easter eggs were fun to find, and a good feature in my opinion.

Negatives:
• As others have already mentioned, the 1-Tower secret exit is completely blocked off. This makes it impossible to get 100% completion, and that's a pretty big flaw since some people are going to spend hours looking for a secret exit that isn't there.
• There are several star coins and secret exits that require power-ups not found in the same level. While this was done once or twice in the original NSMB, it's not a good idea to use the concept too much, as going back to old levels just to get power-ups isn't fun, especially when you can't save until post-game.
• A flaw I also (strangely) found in MF64's hack; World 6 is a second desert world. The other world themes you replaced were fresh and original, so why on earth would you replace World 6 with another desert world? You could have kept the original mountain theme or done an awesome new theme entirely. You pretty much threw a huge opportunity down the toilet.
• It's not a huge problem, but 5-4 is nearly impossible. It's basically kaizo-esque. I had to use a mini mushroom to bypass the precisely timed jumps, and even then it still took 15+ attempts. Throwing a level that hard into the World 5 mix isn't a great idea.