First off, make no mistake - this thing is big, heavy and louder than you can imagine. It was built for a different era when PA systems weren't really made for guitars, so guitarists had to lug their own PA systems around in the form of these monster Marshalls and multiple 4x12 cabinets.
But, the price you pay for your commitment to that mass and volume (you will need to crank it) is THAT tone. You know, the one on all those old records. The one everyone wants, whether they admit it or not.
Mix it with a Gibson guitar and some nice Greenbacks and you're in heaven. It does everything from clean and understated (not at these volumes!!) to saturated, heavenly drive. All you need to do is turn your guitar knobs a bit and vary your pick attack.
What a wonderful piece of kit...