Mine arrived yesterday. I listened for an hour or so last night, and maybe another hour now. My initial impressions are surprisingly good.
The first thing I noticed is that the soundstage is much wider than expected. Very good, in fact. Comparing it to the Hidizs AP100, which I've also been playing around with for the past couple of days, the AP100's soundstage is only slightly wider. As Peter stated in his impressions earlier in this thread, there are some issues at both frequency extremes. Bass is there, but lacks impact - certainly better than the Kogan, but not great either. Last night, I found that the treble could get very harsh - almost painfully harsh on some recordings. Now, with about 15 hours total playtime on it, I'm not experiencing as much of the harsh treble (burnin?). It is rolled off a bit at the high end, but not as much as I expected given the other comments here. At this point, it's hard to say exactly what's going on with the treble, but my initial impressions often change over time. It seems to perform noticeably better on very, very well mastered recordings. Last night I was listening to a Japanese audiophile mastering of the first Blackmore's Rainbow album and it sounded stunning. Not sure what that means. Maybe it's just brutally ultra-revealing? Not sure if "burn in" could be a major issue with something like this, but I'll probably leave the X02 playing for several days to see if anything else changes.
The UI was a bit of a nightmare at first, but I've actually gotten very used to already after just a couple of hours of use! The volume buttons aren't as much of an issue as you might expect. You hold the VOL button down for a long press, and then a volume meter shows up. You can then use the Left/Right arrow buttons to control the volume. What is a bit frustrating at first is the fact that you have to use ONLY the Left/Right arrow buttons to scroll through the menus. What makes it frustrating is that all of the menus are organized as Up and Down lists. Even the volume meter moves Up and Down Your brain subconsciously wants you to press the Up/Down buttons to scroll through the menus, so you will often inadvertently press them by mistake. As I said, you do get used to it in time. After just two hours of use, I'm surprised at how intuitive it's become for me. It's actually easier to control than the maddeningly counter-intuitive FiiO X3. I never got used to the X3's absurd diagonal control button layout.
The X02 can build a database/library based on tags, but when I did that, it completely ignored 2/3 of my files (and my tags are flawless - and I use only the artist/album/year/track/track number tags). Also, when playing by category, for some weird reason it puts all the tracks in alphabetical order, ignoring the track numbers.
The way to use the X02 is the way I use all DAPs anyway, and that's through the File Browser. With the File Browser, the tracks do play in proper numerical order as well (perhaps because all of my tracks are tagged with track numbers?). In general, File Browser navigation is actually very much like the Kogan. I noticed that within the File Browser itself, my album folders are not exactly listed in alphabetical order. In that mode, think it does read the card in the order the files were written. So if I add a few new albums folders today, they will appear at the bottom of the list. Using software like "Copy in Order" would probably resolve this. The Kogan reads cards exactly the same way too.
The UI is nowhere near as primitive as you might expect. I was surprised at how incredibly fast the response time is. When you press one of the control buttons, there's a reassuring click and instant response from the UI. There are even proper even fast-cue and fast-review functions when you hold down the Left/Right buttons when a song is playing. Even the Hidizs doesn't have that basic feature. Technically, the X02 does not support gapless FLAC playback, but the gaps between the tracks are actually very short. Just a brief instant. The AP100, by comparison, pauses for nearly two seconds between tracks (but Hidizs has promised gapless support in the next firmware, due Jan 2015). The X02's onscreen graphics are logically laid out, easy to read and really refined looking, which was another big surprise to me.
Battery life appears excellent. I'm guessing 30 hours or so (mine's been running for about 15 hours total, and the battery meter shows about half power), but I seriously doubt the 80 hours advertised is realistic.
I don't understand the negative comments about the display. It's low resolution, but it's fine. The album art is a bit blocky, but who cares? The font is big, but easily legible, which is what really matters. Brightness seems more than adequate, and it is adjustable too.
The overall build quality, form factor, and design of the X02 are among its best assets. The unit is very small and thin. It's plastic with a thin rubberized coating all over it. It feels great in the hand, is likely very resistant to drops, and looks quite elegant. As I said, the control buttons are very responsive and have a nice feel to them when clicked. The finish of the housing is flawless. Even the small print on the back of the player is sharp and clear.
Although the X02's audio performance is surprisingly good - better than anyone would expect, the most impressive thing about it is the fact that it costs $16. That is, $16 shipped to your doorstep all the way from China! That's less than half the price of a Clip+. Sure, it doesn't sound as good as the Clip, and it doesn't support the finest UI ever conceived (Rockbox) like the Clip does, but it does look a whole lot nicer thean the Clip, has a bigger display, and that "exotic" factor we all secretly love. Oh, and did I mention it costs $16?