This seems to be one of the many Super Mario World sequels on the site to date, with the same old storyline and goal. While there isn't anything necessarily wrong with that, I still think that the author could've done a better job.
Overall, the hack was well designed and fun to play through. The levels felt similar to SMW's original levels, but also felt different at the same time. However, as I progressed through the game, it started feeling a little bit repetitive; this mostly being the case in the later worlds.
What I also noticed is that there wasn't really any consistency in the level design either, meaning that some levels were either pretty long, or very short. Croissant Valley 4 is a good example of a level being a bit to short.
The difficulty was kind of weird in this one. While I do definitely agree on this hack having the "Normal" difficulty, I felt like the levels in the game were only getting easier as I went on. Having a few tough jumps or some annoyingly placed enemies here and there isn't all that bad, however, that really wasn't the case here. At times, I could just run through a level without any of the enemies halting my momentum. This is something you really do want to work on, because a game is only supposed to become slightly harder over time, and not easier.
I would like to add that I found the switch palaces to be rather unique about this hack. Having an actual goodie you can collect makes the experience a lot more fun, especially if you don't even know what you end up getting.
Despite everything mentioned above, there are unfortunately a few flaws I've found. These being level designing flaws to broken graphics.
Seeing as you were limited to only SMW's default assets, a lot of tiles were cut-off such as question mark blocks being placed in the middle of the dirt, pipes being connected to stone, dirt going straight into the side of a pipe, tree trunks placed on top of ledge tiles, etc. While the original SMW may have done some of these few things, I personally think this should still be prevented as much as possible. 
Apart from that, some levels reset the music upon entering a sublevel that uses the same song. Why this happens is a mystery to me, however.
Before I get to the flaws in some of the levels, there's a little typo in this cutscene. "lat" should be "last" here. 
Starting off with Vanilla Island 2, there are some blue coins that lead to a trap, which, I must add, can not be seen beforehand. There's also a dragon coin right above the Munchers, which can be tricky to obtain without getting hurt, but it shouldn't be too difficult to do that. 
Also, just one minor nitpick in the same level; it'd look a lot better if you connected this little bit of elavation with the floor below it. 
Vanilla Island 3 had a dragon coin that was obtainable, but wasn't reachable unless you take a forced hit. Immediately turning around while shooting out of the pipe won't turn you around in time to actually land on the pipe itself. 
In Larry's Castle, there are some spikes that go all the way into the floor, but will still hurt you regardless, making it impossible to collect the blue coins that are above it unless you take a forced hit. 
In Croissant Valley 2, players can somewhat exploit this level by swimming underneath the ground here, this could also get you stuck once you've activated the green switch, and if you're small Mario. This can easily be prevented by placing solid tiles under the ground, which you did do later on in the level. 
I'm assuming you forgot to place the rest of the pipe in Croissant House. Entering the pipe will make Mario visible as he goes down and dissapears the moment the screen transition occurs. 
Croissant Valley 4 suffers from severe slowdown because of all of the dolphins and the Porcupuffer. The reason I pointed this out specifically is because this is the only level where I've encountered this kind of slowdown.
Teacup Forest 4 has without a doubt the biggest issues when it comes to sprite memory. The large green bubble that appears at the end almost has all of its graphics missing due to the large amount of Boos on the screen. 
And the final flaw I've come across is the fact you can jump over the stage in Cream Fields 2, and end up getting stuck in the grass as shown in this image. Again, this can easily be prevented by placing solid tiles on top. 
It was fun playing through this hack, and it's definitely one of the better hacks on the site. Unfortunately though, seeing as the hack isn't necessarily unique, and doesn't really have anything new when it comes to gameplay, style, graphics, music, etc, I'm voting for this hack to be rejected