Tip: When determining a time limit, remember that players won't be as familiar with the level as you are. If you normally complete the level with the timer around 100, others might run out of time on their first try.
Oh god i lost it completely during the ending and credits
But seriously, this hack is incredibly well done and is only bested by Star Road
The level design is amazing, although it suffers from 'World 1 syndrome' (a term I made up). Other than that I found every level amazing, although the secrets are a bit undetectable at times (I know about what happened in 1.2 btw)
Rainbow Star Haven has to be one of the best levels I've payed in a long time, and the secret Temple was, although difficult to discover, a great secret level in its hidden-ness
The Hub is amazing, I found it entertaining how Mario zigs in the wall, and worth the glitch
My only problem is the aforementioned 'World 1 Syndrome' and that Dark Dank Abyss was a little boring IMO.
TL;DR: Great hack, the minor glitches were little problem, World 1 was iffy though