I got my mocha box boots in November and I've had no problems whatsoever- no blisters, no trouble getting them on and off, etc. I spent two days going back and forth between two sizes, two pairs in each size. I ended up with the 1/2 size larger ones and couldn't be happier. Boots with a straight back should have some heel slippage in the beginning. The slippage decreases as the boot becomes more pliable and molds to your foot, which only took two wears for me.
I will say that these boots should he tried on before purchasing. I went a 1/2 size larger than I normally wear in H shoes, but for others it might be a 1/2 size down. There can be quite a bit of variation since these are handmade - two pairs in the same size are likely to feel entirely different. Once you find the right fit, they are perfection. I am thrilled with mine!