I've been using my Gold 2.0 Pistons primarily for audio book listening, but been listening to music with them for the past week. I love the Android control compatibility, and that they stay in my ears (big problem for me - finding the right IEM tip). For music listening while walking out doors - rock, post rock, electronic and new classical - they really shine. The only album that let me down the Flying Lotus CD mentioned I already mentioned in a previous thread. I think that for most listeners (not the majority of head-fi-ers) using a decent smartphone without an amp, the Piston is all they need. For more critical listening I use my Vsonic GR07 classic, but for listening to something noisy with imperfect recording methods, like White Fence, listing with the GR07 is an excruciating experience. Also, the GR07 feel delicate. I only use them indoors or on a flight with foam. I wouldn't use them at the gym are rarely when walking around outdoors.
I believe the hype. The Piston provide a fun sound for non-critical music listening. KZ ES on the way. I'll compare those to the Pistons next month.