Simple, yet complex. The problem I find when doing circles is, how do you, as a homebrewer, cut out the label to put on the bottle? That's where I find squared, rectangles, and diamonds a much easier design to work with. Making a really nice label, then having to delicately cut with scissors or a razor around all the details (or even just a plain circle) leaves alot of room for error, making the label look like crap when you slap it on the bottle. I guess a plain circle would work if you had a stencil to cut it out with.
Anyway, good work.
PS: I see you used the same 'shape' as I did in my label. It just...works. (see Black Mamba thread)