Feature:
The features are that which make this unit incredibly powerful for use in learning and teaching guitar (or any instrument) parts of songs. This is where this unit shines: it is incredible! I've never experienced another machine or software do what this unit will do. The four or so "filters" which are included, will remove various parts of the tracks (including the majority of the vocals) and "feature" or "play" other tracks so that one can hear clearly various parts of a song: e.g. with U-2's "Vertigo", we could hear The Edge clearly play his guitar parts by removing other parts of the band's tracks. It's absolutely incredible to use this way and there's no other tool like it that we've seen. ("We" are the several instructors at the music store.)

Quality:
The quality of workmanship seems fine in the month that I've put this unit to very heavy use during a 50 student work-week. The students love this machine and are intrigued by it's ability, looks, sexiness, and sounds. Like I said, at least 30 students per week use this machine with me and we love it. We do not use it for vocal use - only to figure out guitar parts for songs with and play guitar along with the them through separate guitar amps.

Value:
Many of the guitar teachers (and the store owner) where I work are getting excited over this new tool, and want to use it for teaching their students new songs. We all think this is the hottest tool for learning and teaching songs in a long time.

Desirability:
Every student who came into my teaching room the first week I had this machine, took one look at the beautiful and sexy blue lights on the unit and loved it. At first they wonder what it is; then after they use it they want one as well. The students and myself love the various sounds that the "filters" or "vocal removal settings" allow us to hear on each CD as well as the ability to slow down or speed up the songs, and change the pitch without retuning their guitars to learn the song playing.

Sound:
I am a professional guitar teacher and use this unit at with at least 30 of my 50 students per week for learning, teaching, and having them play guitar along with new songs. The sound quality works just fine through small, amplified Roland speakers. We have had no problems at all with this unit regarding the sound, and in fact it can get much louder than we need it to be (plenty of gain).

Support:
I have not had to request support for this product. It has worked fine.

Overall:
At the music store I teach at, we're all intrigued and excited by this new tool to learn and teach songs. It's a "keeper" and the coolest thing we've seen in a long time. I wouldn't be without one now. The next step is to replace our CD players at home and at work with the Alesis Playmate Vocalist. Why have only a music playback machine when you can have a unit that will give you so much more flavors of sound?