Received mine a few days ago, just got around to opening. 2/3 working perfectly, but with the black one, the plastic stuff sealing the actual watch part seems to have a bubble of air in it or something. Still works, just a little weird. If it bothers me enough, I think poking a small hole with a pin would work to let out the air, and then I could use a low-temp glue gun to seal the hole so it'd still be water resistant.
For the record, I got all 18 cm in grey, black, and purple.