Feature:
Those beefy carved-in handles that don't crush your fingers and just plain don't exist on any other cab. The casters (my saving grace). A tweeter with a light bulb is really nice to have (having fried many on other cabs) as well as the ability control the tweeter's level on the crossover. The only issue I really have is my grille rattles a bit.

Quality:
If anything YOU are not made well enough for this cab... It keeps you from becoming the fat bass player, at 118LBS you'll have abs of steel and a back of frail driftwood. Mine has been dropped, knocked, peaked, burned, spilled upon, in freezing temps, blistering hot sun and (my favorite) driven 40 miles cones up in LA acid rain by an idiot I no longer talk to and if anything, it sounds better. I just don't worry about it, it's a TANK that proudly shows you where it's been over the years.

Value:
I've had this cab new when they were first being offered for an absolute steal and I'm glad I did. This is the cab people are going to shell some serious cash for in another 15 years so get one now while you still can! IT IS WORTH IT

Desirability:
One of the if not "THE" sexiest cabs I've ever seen--especially for the fact that it sounds even better than it looks! From the curvy birch to the massive grille to the sleek handles to the ports that look like they're going to shoot flames and the classic ampeg type carved into the side, you tell me, what cab looks sexier and sounds as good? I like that mine has a billion scratches.

Sound:
That bumpy, big butt, buttery popcorn low-mid ampeg sound all the way down to 18hz. Always cuts through, always heard on stage. I've put this against so many different cabs including every one that Ampeg made when mine was new, there was no comparison at all.

Ease of Use:
I used to run a SWR SM 900 through it and coupled it with a mid-rangy carvin 210. Now I run an old Carvin PB 500 mono through it stand alone and it sounds perfect. Over my time with the cab, I've gone from loud heavy rock to Motown funk infused band and it just followed me into it. In a nutshell, it compliments anything you put through it.

Support:
I haven't had to deal with Ampeg because my cab has never had an issue. I would imagine however that Ampeg is one to the top companies to deal with in terms of Customer Service.

Overall:
Forever, I've never even needed to think about buying or expanding to another cab, if anything I need something smaller for smaller gigs. This is it. If I can help it, it will be in the family for generations to come.