I've owned one of these heads for about 10 years now. It's been a very reliable unit and you can coax killer tones out of it. The dual preamps make a huge difference...you can solo them or blend as desired. That alone usually means I don't need to use the EQ at all.
Want more Motown or a gritty Live at Leeds kind of sound? Roll off the solid state preamp, and dial up the tube. Overdrive on demand! More hi-fi? Go strong on the solid state pre.
Gobs of power in this thing, too. Pleny of overhead for almost anything. I've most recently been running it through a ported 2x10 and it sounds absolutely amazing.
Beefs: Not many.
-I wish it had a tuner output (an A/B switch takes care of this).
-The cooling fan is slightly noisy...not a problem in a club; can be undesireable in a theater show or studio if you're using mics to record bass. I'm going to replace the fan with a quieter aftermarket unit because of this.
-The one-dial onboard compressor should be considered worthless unless you stricty look at it at a peak limiter. Use an outboard compressor if you really need one.
Regarding previous comments about the tube side going out...I last replaced my tube (yes, it's a real 12AX7, not an emulator) about seven years ago, and it's starting to go again. So, I'd say count on replacing it about every seven years. Tubes do wear out over time, replacing it is cheap and fairly easy. That tube can be found almost anywhere.