Good Use of Time
The opening part sounds to be pretty good to me, though maybe it does take a while to build into the main song, some parts do repeat in a funny way, though I like how the main background repeating part changes from side to side of the speakers, sounds nice. The slow build up is actually pretty good for a long song, gives plenty of listerning and it's not that easy to tell how much has been added since the start when you slowly build it up.
Removing of some beats and adding new ones though the main tune is good and keeps it kind of fresh. I didn't like the whole sudden change in the middle part though, I think that could have changed over a little smoother. Though the beats in the changed part do sound good and everything, they work just like with the opening part, just the sound is a little sharper.
It doesn't actually sound all that repetative for some parts but there are parts where it does sound a little too repetitive but for most part it seems you have kept it fresh with new beats. The change at about 4:40 was good though, that seemed to work better than the previous change, the beats in the last part are good, much like the rest of this.
Overall, I think you have used the time well, plenty of verity in this but the only thing that lets you down for me is your first change in beat style, if it wasn't for that, I would have enjoyed this much more, but good work.
4/5
<3