FWIW, I have had/own several high end Walkmans (S Master amp),, clip zips, iPod 5, 5.5, and 7th gen video/classics, Nano 3rd & 4th gens, iPhone 4, 4s, 3G, & 5, Nexus S with Voodoo (has Wolfson), Xperia Z, Zune 30, 120, Fiio X3, and have the HiFiman HM-601 and recently bought a Zune HD.
It's pretty flat, not as neutral as the Zune 120, but the cleanest with the best micro details of all the Zunes. Great imaging, good separation, and a higher output volume wise than a clip. Colorfly c3 etc. (mw)
I agree it is handily better than any iPod/iPhone and certainly worth owning if you want a great player with the benefits you will have to forgo in the "audiophile" grade players. The only consumer product that rivals it in my mind is maybe the Walkman F806 that I have heard, but this again, has more power than even that for my iem's.
I wish they still made new ones to be honest. Everyone of them I have ever owned ALWAYS improved over the older model SQ wise which is more than I can say of any other company I have had experience with (as far as never going backwards).