Pros: Huge, rich, detailed sound, great build quality, all-in-one, android UI, very powerful
Cons: Requires to clean up you library, a bit large, fairly poor battery time, still some bugs to be fixed, no USB charge
When I first received my iBasso DX100, I think I lost a week or so really getting everything to work perfectly, even though I had solid advice from other headfiers (see the FAQ on the player), and even if I went straight to 1.2.7 firmware.
The main things that will take time is that you need to clean all your tags (I thought they were clean, but apparently not DX100 clean). Then you have to understand the small issues (for instance, when you turn it on after transferring a lot of music, you have to leave it alone for a long time, even if it seems to be doing nothing, or it will freeze - for the longest time I thought something was wrong. Apparently they will fix this in the next firmware).
Once you overcame this initial phase...well this is another realm of sound. I can only compare it too my previous players (ipod + ibasso T3D, Cowon X7, Cowon Z2), but the gap is just huge. For instance, if the sound is 4/10 for an ipod and 6/10 for a Cowon, it's gonna be 10/10 for a DX100. You really have to listen to it to understand the difference. With good IEMs (top tier universal or customs), the feeling of space and instrument separation is just huge. You hear every single detail in your music, which may be anoying with low quality music. And when I say low quality, I don't only mean losless vs. mp3. Some CD quality tracks may be poorly mastered and have a lot of noise. The DX100 will let you hear everything, for better or worse...
I don't want to get into the whole technical analysis of the sound, because I am not qualified too, but just to give you an idea of the quality: there is a track on fiona Apple's latest album called "Werewolf". The song starts with doors opening and closing, with the sound coming from the back. I was listening to it alone in my bed and really stood up and looked around terrified, convinced that someone had entered the room.
In my opinion there are two main issues with the player: the first one the battery does not last very long, and for reasons unknown to me the battery life seems a bit unpredictable depending on what is running in the background (I don't want to risk rooting the player to remove all unnecessary apps). The second one is that the player is not all that portable. It is not only the size, but sometimes, if you really move it around too much, the music might skip. So in my opinion, this is not the player to run or exercise.
The last problem crazy audiophiles may encounter is that they will not know what to buy after that ! It seems like the best all-in-one portable solution out there, and you will even hard pressed to find an amp to make it even better ( according to all the reviews out there, only the best portable amps make it marginally better, but I have not tried it.). So your purchasing mania might be frustrated :)
All in all, I just love this player. I have been listening to twice as much music since I have it, and this will only get worse (better) once I get my Miracle. If you are looking for amazing sound and can overcome a few niggles, this player is for you.