Feature:
It's light. Both components are under 50 pounds. And it's freakin loud. I play in a band with a couple of full stacks and a loud drummer, and I cut right through, no problem.

Quality:
Don't like the attached power chord much. That worries me. Otherwise, the cabinets have 2 locking features and are very secure when stacked. Spray on coating seems durable, and all controls are recessed.

Value:
It's a bit pricy, but you definitely get what you pay for. Super light, high power bass rigs just didn't exist before this. I paid $1850 for the 210 and the cabinet at a local place. That's a lot of tone for under 2K.

Desirability:
It's Light! It's Loud! It Sounds GREAT! And it's a bass amp? Wow!

Sound:
This is a very high quality amp. The three COSM Models are all useful, the compression is subtle and effective, and it has a very controllable sound. The horn control is on the front of the amp (duh!, why are most in back?), and with very mild EQ-ing and horn adjustment you can get razor sharp highs and big, controlled lows. I've owned everything from SWR's to Ampegs, to GK's, to full on rack rigs, and this thing simply sounds great. I use the 210 model, with the 115 extension cabinet. I'm using the extension as a sub, so it's actually a tri-amp setup. It sounds killer, and the amp is dead quiet in between notes, even cranked. Use a Carvin Icon and a Warwick Thumb fretless. Play a wierd metal/jazz hybrid style of music, and run a lot of effects.

Ease of Use:
Simple as it gets. Sounds good flat, minor tweaking yields major results.

Support:
It's always a 10 when you don't ever need it. No issues.

Overall:
I'm saving for a second set so I can run in stereo. I'm selling my GK 2001 RB and 4 GK 2 X 10 cabs because this set-up sounds better and is PLENTY loud. Stereo wil be very cool.