Well... yeah. The mids and highs get mushy (occasionally). Usually it's not a problem but these headphones always scream "bass"
I'm not really sure how they sound compared to the MC5 (which is more of a price competitor) but I think ADDIEMs are a bit more treble-forward (there's a tad of coloring), like MC5's will come across to you as clean and very neutral. I don't really think they're too bassy but I think a tad more then like MC5's. Are they a huge improvement over Apple earbuds? Well, two very different form factors. As far as the sound goes, I can say they're a pretty big improvement, but whether they're an $80 improvement -- that's up for debate.