Pros: Remarkable SQ, plenty of power, plays pretty much any format
Cons: not cheap, buggy software, shortish battery life
Bought as part of my upward spiral into high quality portable audio. I wanted something to surpass my Cowon J3 and the DX100 certainly achieves that.
The sound quality is better than anything I've ever heard. This is not, of course, an exhaustive list, nor do I have any home audio to compare with. I'm not really an audiophile but I listen to 2-3 hours a day while I commute. With this and my ACS T1 custom IEMs, the rest of the world just vanishes into the background. It's just as well I get off at the end of the line or I'd miss my stop every day.
The interface has not been well received, but coming from a J3, it's certainly no worse, and as someone who's been using Android for a while now, I found it pretty straightforward. I'm getting about 8 hours battery life, which is safe for two days of my use, but does mean I need to charge much more often than the J3.
How good this would be for you depends on what you want. My only need is to listen to good quality music, one album at a time, for as long as my journey takes. The DX100 has given me more pleasure whilst fulfilling my simple needs that I thought possible. It wasn't cheap, but I've found it to be worth every penny.