Pros: Tiny, extendable memory, rockboxable, handful clip, reads FLAC, dynamic playlists, astonishing price/functionnality ratio
I bought this DAP for $50, along with a 16-GB micro SD card that cost me $17. So I've got a total capacity of 18,4 GB in a DAP which is 5,5 cm long, 3,5 cm wide and 1,5 cm thick for a total of $67. Less than the third of the price of an iPod nano that has less than 16 GB of memory.
It does everything I expect a DAP to do : it can sort tracks by folder in addition of all other ways, it allows dynamic playlists, it can play FLAC files (even if I never use this feature), and many other. All you can wish, I guess. The only things I miss don't even come from the DAP itself, but from Rockbox : to me, it lacks a "stop after current" function, as in foobar2000, and a "clear playlist" function.
I rockboxed it immediately after having receiving it. Rockbox adds some useful and other funny features, like radio recording and some games like Sokoban and chess.
The writing speed in the Sansa's memory is around 2.70 MBps.
I can use it for between 12 and 13 hours before having to charge it.
I've never used it with the default interface, it has been Rockboxed the minute I opened the package. The interface is extremely intuitive, but the Rockbox manual is useful for "advanced" features.
It is very reliable : it fell on the ground several times, sometimes king of bugged, underwent countless formattings, firmware re-installations and Rockbox installations, and works as well as when I turned it up the first time.
And finally, as for the sound quality... well, I can't complain about it. I never spotted any lack of details or coloration compared to my GrubDAC. Even amped.
I truly think buying this DAP was the best thing I could do with 50 €.