The velcro NIAD feels a bit softer and smearier than it's lace-up counterparts. It is generally favored for slab climbing, gritstone climbing or indoor use, whereas the lace-up versions are preferred for standing on little edges - so perfect for limestone.
This really is a toe crusher though and the uninitiated are not going to find this very comfortable. The really aggressive heel forces the foot into the front of the boot, bunching the toes right up and eliminating space.
A common mistake with this shoe is fitting it too big, meaning the heel is not stretched out properly and leaving a big pocket of space at the back. That being said, even if you go really small there is still a chance there will be a bit of space around the heel.
Once you are used to these however they really are one of the best face climbing shoes about.