I have an X Cube II. I have had it for over two months, and honestly, they are many days that I want to throw the damn thing at the wall, pardon my language. I will say that, while the battery door has a tiny bit of movement, mine's not slippy slidey like some people's. But the firing bar is wobbly and makes building on it uncomfortable, and there is a delay between when you fire and when the coils begin to heat up. This is annoying for checking coil performance, and causes flavor builds to under-perform, unless you chain vape.
The top screen, while easy to read, is often in my way, and now that I have an RDA, I'm very concerned about juice or condensation getting in via the buttons or screws at the top. Condensation also constantly blurs the screen and the finish is a fingerprint magnet.
Because of these issues, I'm going to be buying an RX200 as soon as I have the funds to do so, and vaping this device forward to someone who can make use of it.