Gothenburgmetalmix

Overall, really good mix! It also helps that I like the song too :). Here are a few things I would address about the mastering:

The rms is -9db, so a slightly more dynamic mix would be nice. This could be why it sounds like it's distorting. Of course there are pro mixes that are much worse than that, but for me that's just personal preference.

Eq wise, I think there are too many sub lows (70hz and below). bring those down, and bring up 70hz-350hz to make the bass and guitars sound more full. Also, I'd make cut around 2k-7k, and boost the 9k-15k region.
 
and just for kicks, here's a little remastering i did with the track.

http://files.getdropbox.com/u/333261/circle remastered.mp3

with eq settings:

mastering.jpg
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hope this helps
 
I may have gone a little too far bosting 125hz, but you get the idea.

Technically, any hard limiting is distorting the sound. To answer your question, yes I hear the "limiting" going on, but i wouldn't say it's distorting, like as if my speakers are blown. Using this much limiting on an audio track CAN make SOME speaker systems sound like the speakers are distorting.