i really like the second tag, and the render you used in the fifth one ;).

i feel like the third would benefit from a darker colour scheme, especially since i don't like the colours used - there are multiple focal points in the third as well.

that shape on the left hand side of the fourth one ruins the whole piece, and the lighting on the first one is off (there are shadows under her chin and on her neck yet the light is behind there).

overall there's some great stuff here but some of it needs work, you seem to go a little overboard with effects. :)

Jakey, pretty much nailed it.
The 2nd is great, the others need more work.

I think your biggest weakness is coloring.
Most of the time the colors are kind of dull and lack vibrancy.
That might also be why some of these tags appear really flat (e.g. 1 & 4).

I kind of like the third one, but there are too many different colors in it and I don't like the motion blur stripes.