Very good. Lightweight. The battery lasts with everything open. The NFC works great (for Ethniki for sure, I think you can only use Mastercard).
However, it has two or three software bugs that need fixing. I hope they will fix them in an update. It doesn't read the emoticons that people send you (it shows some boxes). It also doesn't notify you of video calls, so if you don't have it nearby, you have to be called as a regular telephone call to see it on the watch and then open the camera to video call.
Also, you can't end a call with an automatic message in all applications. It only works in regular phone calls. In messenger-type applications, it simply has a rejection option.
However, these things are easily fixed, especially on a watch that costs 40 euros, they are minor details.