Feature:
The unit does not come with an adapter, but it charges an internal lithium-ion cell that can easily be charged through the supplied USB cable using a computer.

Quality:
Seems well made. Has an aluminum body that should hold up well. I haven't dropped it (yet) so I am probably not the best judge of who well it is made.

Value:
Good value, in my opinion.

Sound:
Sounds fine, but it does not crank out much volume. This is the reason that I did not rate this product higher.

Ease of Use:
Pretty easy to use but does take a bit of time to understand how to get to some buried features. Some items that would seem intuitively to be important enough to need easy access require a bit more digging through the interface (not a big gripe though).

Overall:
This device makes learning bass parts easy. Looping through a troublesome section of a song is very helpful. It is a bit touchy about the type of MP3 that you can use. I did not have a problem with this but in reading reviews did notice that others did. 98 percent of my MP3s are recorded from my personal CDs at 160Kbps at 44.1KHz. It does not like variable bit rate files or 48KHz files. I was able to put about 220 song files on the device. All of these files have intriguing bass parts. I will probable never learn to play all of these songs, but they are handy if I want to try. Cool device!

Feature:
doesn't play half of my MP3s. I get an "Unsupported error" when I try to play the MP3. But these MP3s play on all other MP3 software/players on my computer.