But to put that in context, it is still the most fluid and fast UI in a dap currently available, (even bests the AK240). Yes the latest smart phone is a bit faster, they have quad core cpu's vs the dual core in the ZX1, and they also use a lot more battery. Sony made a good choice with the ZX1 balancing high performance with battery life, most other dap's use much slower cpu's than the ZX1 still.
Ah yes true, but also coming from using Android since the first Galaxy S - which was what, 4 year ago? - and iPod Classics and the NWZ-A867 (fast in general but soooo slow with playlists) I'm quite happy how responsive the system is AS A WHOLE, at the same time with how advanced touch screen technology is now and maybe compared to other similar Androids the touch screen is one of the only things I have a tiny niggle with.
Correct me if I'm mistaken but I'm guessing Sony is marketing this as a mainstream entry into the audiophile world, and maybe it's just an issue with the music app but for me I was just a bit taken aback how multiple taps wouldn't respond when my previous experiences with touch screens has been so consistent. So for me it's not really a question of high performance/battery life, but the quality of the touch operations. Like you can see the app feeding back as an entry turns blue when you touch it... so it seems the player is keeping up but for some reason it doesn't play the track.