Okay...some thoughts on the M1. I had the pleasure of borrowing a unit from someone for a week and spent a little time with it. I used it strictly as a DAP. No bluetooth, no DAC, no nothing. Just plugged my cans in and enjoyed it. I used my DIY Ypsilon woodies, the VE Monk and the Quian29.
It has that Shanling signature. Everytime I hear one of their devices, it's there. Smooth, sexy, very pleasing. Not too warm, but definitely not bright. Its a sweet little Goldilocks kind of thing I suppose. I preferred the M1 to my Sansa Clip+ (Rockboxed) and my iPod Classic (modded to 256GB SD storage). It was bested by my Aune M1s and my FiiO X1 (gen 1).
The scroll wheel doubling as the select button was a little annoying, but not a deal-breaker. The device is small though, so holding it in my larger-size hands (I'm a bigger guy...6 foot 3 inches) and manipulating the scroll wheel, then having to use it to select as well got a little fiddly at times.
I had no software problems, and I liked how the display filled with the album art when it was available. I am also glad the screen is not a touch screen. Lord, what a nightmare that would have been.
For the price, I really liked it. Well worth it, especially as a backup device in your backpack, or for walking around town.