I've had mine here for awhile now. The only issue I can see is that while the tyres are perfectly moulded with excellent tread pattern they are very stiff. To get them on the rims I have had to soak them in hot water to make them pliable. I have read on other forums where Belkits earlier releases are having issues with the tires eating the rims after a period of time.
I had a 1/12 Tamiya Porsche arrive here and the roof was a bit pushed down due to poor packaging and the postal service putting too much weight on top of it I was gutted at the time but probably a year or so later I opened the box and the body shell looked perfect. I can only guess that the plastic had a memory.
I've made several purchases off Gravity and they all went like clockwork. I tracked the order all the way from US to NZ with out an issue. On more than one occasion from several different companies I have been given tracking numbers that didn't add up. Everything to date has eventually arrived here so I've never worried about it too much.