I ordered these boots in a size 12 (this seems to be the right size for me in most cases of a closed shoe) as I was looking for a slim fitting boot to wear with skirts and leggings. The price was great on sale ($139 CDN?). I am 6'1" and generally a size 6 in pants, slim calf. These boots had a pretty nice fit from the ankle up, but not as snug as I was looking for. The front was right up over my kneecap and can be folded down, which was quite cute. The problem was in the fit of the foot: for a 12 they were massively long, too wide for a medium width, and very loose in the heel. If you have a wider foot and a thicker calf they would probably fit great.
Incidentally, I also ordered the Briaca boot from 9West at the same time and they had a similar fit in the foot--baggy and shapeless. In the case of the Briaca, the shaft was lower but fit tighter to the leg. I'm a little surprised at the poor fit of 9West boots this season (Perla is no exception--sending those back tomorrow).
Again, a good suggestion to LTS in this regard would be to post reviews that customers are leaving on the actual website so we can make better ordering decisions.