Literally, just opened the box (DHL dropped it off outside the door without even ringing a door bell, good thing I checked cause we are expecting a storm over night). Just spent a few minutes with it, copying songs, then a very short listening/comparison to X7.
UI does feel faster, and what I like - they changed the GUI of the main Playback window, a lot cleaner now with a slim scrub bar to fast-forward through a song, and track/artist name underneath, and clean layout of play/pause/skip buttons; all the extra stuff (eq, bluetooth, favorite, etc) is hidden and accessible from a pop-up animated menu behind (...) icon.
Comes with a default AM3a balanced module, but I only tested SE output between X7 and X7ii (just a very quick test). Seems that AM3 has a little more power in comparison to AM3a. Right away, I can hear a wider soundstage. Tonality is similar, but I do hear a little improvement in dynamics, maybe even a little better layering of the sounds, nothing really night'n'day yet (except for a noticeable soundstage width improvement), though too early to talk about it, I want to let it play over the weekend, to condition capacitors and the rest of the circuit.
We are talking about dual uSD card (vs single in X7), volume wheel and playback hw buttons (like in X5iii, I was never a big fan of X7 symmetric button layout, never got used to it), backward compatibility with original amp modules, some GUI improvements - all that already a bonus. Plus, Sunny mentioned they have a new FW update which I have to check out. So far so good!