I must say I used to be in your situation. Reading around so much, hearing many many praises for it. And as the result, jump to get the D2.
After a week using it, my opinion is that in term of features, it has everything you need in a DAP: build-like-a-tank, flash, expandable m/c, various codecs ...
However, the most important factor I felt uncomfortable is SQ - or more correctly sound preference. I really couldn't bear its sound signature. My favorite musics are rap/hiphop or sometimes pop. The D2 has one of the most analytical sound. It shows all the details of the song. Fantastic for classical, IMO. However, its dry,cold and lacking-bass discourages me so much. It's absolutely the brightest DAP I've used. And of courses, never fits my favorite musics. I have to turn my attention to the Sony, and feel like home with it
So, if you are heading for the D2, the most important you must consider is whether its sound sig fits you or not. Don't worry about those features because it's simply one of the best right now.
After this, I draw an experience that when you look to a DAP review, just pay attention to their opinions about the features. SKIP their opinions about SQ. They are just the users/reviewers' personal likeness. It may fits their hobbies but may not you. Try your best to audition it before deciding to get it.