The case can have small manufacturing imperfections on the edges (you can easily feel these with the nail). Since it's made of a hard material, that means your stainless steel band will end up scratched (it's happened to a number of people, me included).
I know that hairline scratches on stainless steel are pretty much unavoidable with time but this case is really not helping at all. Also, some of these are not hairline scratches. I have tried the usual TPU case and, despite it's rubber-like feel, these at least are not hard enough to scratch it.
At this point I'm considering to either rock it naked (on the back) or get a back skin but leave the band exposed. My preference would be a piece of tempered glass for the back of the phone but I haven't really found any decent options.