I own another pair of Keen maryjanes and they fit almost the same. (These are slightly longer) The material on these is stiffer, because it's a dressier shoe. The heel does slip. I wear a 3/4 orthotic in my shoes, with the original sole removed to make room. The removable sole in these is about 1/4" and my orthotic is half that on the heel and ball. This explains to me why people are slipping on the heel... Keen's foot beds last wonderfully as I've had my others 5 years and they are still great! My foot Dr likes the foot bed for me too. The roomy toe box is great for feet with pinched nerves!  I can not wear the typical office shoe with my orthotics and these carry the look I need with the comfort I want.

I'm adding to my original review after 1 month.
The shoe has loosened up a bit, making the back slip even more.  I've placed these side by side with my other Keen's and they are about 1/4" longer and the heel is A LOT roomier. The strap is set forward towards your arch, not right in front of the ankle- lending to the slippage issue.  I would suggest people find this shoe in person to try it on. Perhaps buy a step down from your normal size and take it to a shoe repair guy to stretch out the tight spots.  The alternative is a shoe left behind you on the sidewalk.  :(