The Gill boot has a super flexi sole which makes it very comfy to wear.  The boot runs slightly snug.  I wear a 7.5-8, and the 8 fits well.  If you're often between sizes, go up.  The boot shaft is slim, so if you have thicker calves, note the circumference.

The boot material is PU.  I think this is where a potentially great boot went wrong.  The material combined with the zipper makes the zipper bulge.  It's so ugly.  I wear this boot only with pants that hide the ankle.  The Diba Babs boot is very similar except in fabric uppers, and it doesn't have the zipper bulge problem.  If the boot were leather or fabric or didn't have a zipper, it'd be fabulous.

It's a comfy boot at a reasonable price.  Just don't plan on showing it off with skirts.