I've had the 3fvape version for a bit now. Temperature control works on it. Seems like it works as designed a little better if I'm not at 40w's. Might just be whatever build I have as I'm not experienced with nickel. My biggest issue with the device is the 510 connector. It's not floating, and it's not reverse threaded, which means if I want to switch between my kayfun and my dripper I need to have a flathead screwdriver on hand, because otherwise it's not going make the connection. Also kind of weird, when I use my kayfun v4 clone (1.3 ohm kanthal single coil build) on it, it asks me everytime I bring it out of sleep mode if it's a new coil. If I tell it it's a new coil it operates as I expect. If I select same coil it thinks it needs to do temperature protection, and because it's not nickel, it doesn't perform as you'd expect. It doesn't do that with the Atlantis tank I have, or the nickel coil I put in my plumeveil. Slightly annoying as I mostly use the kayfun lately. Overall build quality I'd give it a 8/10 compared to the real one. There's also a little button rattle with the up/down buttons. The top part of the mod is ever so slightly misaligned. Doesn't bring any performance issues, but when you know it's there, it's there.
I have a buddy at work that has a real 30w vaporflask, Build quality on his is noticeably better. Another buddy has the fasttech 30w model. Build quality between mine and his seems about the same quality, but his has the floating 510. The dna30 clone chip in it appears to be the same as the cana I bought from fasttech.