Even considering the fact this is an old hack doesn't stop me from thinking how mediocre it is, there are enough wrong things in this hack to say this can't even be considered decent.
Level design is a little varied, but it wasn't well worked on. The first impression I got from the first level were long and flat segments, as well copied ones from the original levels of other Mario games such as SMB1 and SMW that were clearly just thrown in the middle of of this overall inconsistent level design work. Other levels that feel different were just short and boring as there wasn't much going on them -- most of time enemies aren't a threat.. they're just there because yes.
The soundtrack is horrible too, but I don't think it's the author's fault on this matter since 2008 ports had almost no quality put on them -- I bet the author would be impressed with how great music ports sound nowadays if he ever comes back to update his hack or something.
I just talked about bad things until now, so let's move on to a few ideas I found interesting: Although it's
obligatory to fly over the wall in Luigi's Lake to proceed to the castle
I personally thought this was a good idea since it makes the player need to play levels that seemed to be just optional at the begin, but that later reveals to have a purpose. Mute City itself also had a good concept, but its design needs more work.
Overall, I didn't really like the hack. You had a very few good ideas, but the bad issues definitely overweight the good things in this hack. I personally don't recommend playing this unless you're really, really bored.