I really like the track! I love circa survive, My friend and I are working on some circa inspired stuff (among other influences of course). I'll be sure and put em up when we're a little further along.
The first thing I'm noticing is some kind of distortion during the quieter parts of the song (opening guitar, piano breakdown). Not sure if that's myspace's doing or what.
The drums definitely need some spaciousness to them, if you listen to "The Difference Between Medicine and Poison is the Dose" you can get a nice reference to Circa's drums without any other instruments.
I think the lower background vocals towards the end need a little mud cut out of them, maybe a little presence and verb added
I also, agree that some bass would round out the bottom end and tighten up the whole song.
Having said all that I am only listening to it through cheap ear buds. I'll have to take another glance when I'm in a better listening environment. Sounds like you're off to a great start!