Positives: I like the song over all. "Instruments" are fun and seem to be well mixed, especially at the beginning when I can hear them separate from the vocals. Catchy tune!
Negatives: I'm not as particular, but yes the compression is too much. The problem is when each additional layer kicks in (the beat at 0:23, the vocals at 0:44, etc) the mix feels crowded, like some items are pushing others out of the way to get to the top.
Notice how the vocals don't sound like they're blending in with the song, and when there's a quick break between vocals, it's almost like the instruments jump up for a breath of air (i.e. get suddenly squeezed louder, and then forced back down afterwards).
I'm no expert here, believe me, but when I listen back to some of my older music I can hear how much I was using compression in an effort to make it louder and comparable to other songs I was listening to.