Feature:
The previously mentioned blend control, an actually great-sounding octaver and overdrive, and the fact that everything is footswitchable fill just about everything I need. The EQ could be a little friendlier, and I'd like to see a ground lift on the DI, but these are small points.

Quality:
This thing is SOLIDLY built. I opened it up to take a peek inside and everything is very cleanly constructed and tightly locked down. Plus, it looks beautiful, which is not something I expect from my rack gear. The brushed aluminum face, large easy-grip knobs and the VU meter make it look like something from a mad science lab. I want to paint my cabs silver to make a science-fiction stack!

Value:
Considering the other preamps I was looking at that cost more than twice the price and didn't sound half as good, I'm thrilled with the value.

Desirability:
It's fabulous sounding, easy to set up, and LOOKS amazing! When was the last time you wanted to show off the look of a piece of rack gear?

Sound:
I upgraded to this from a SWR SM-450, and the sound just blew me away. I'm running it through a Carvin DCM1500 power amp and two Acme Bass B2 cabs. The ability to mix the tube and solid state preamps is fabulous. The solid state end is punchy, while the tube adds some beautiful "oomph" and, with the drive control, some nice distortion. My favorite rock tone is right about 50%. The EQ is a little confusing, but honestly, I've hardly had to touch it. It sounds great flat.

Ease of Use:
I got this without a manual, and was still able to get a great sound pretty easily. Like I've said before, the EQ is a bit confusing (a combination of knobs and sliders, which really do the same thing), but not a show-stopper.

Support:
I haven't had to deal with Ashdown directly, but their website is well laid out, with all the manuals available to download. (I went to look for the manual, eventually. :) )

Overall:
I may be an Ashdown convert for life. I'm so thrilled with this preamp. It has become a signature part of my sound.