It does what you need a practice amp to do. It's great for practicing by yourself or with others playing acoustic. If they're playing electric, they'll need to keep the volume down or the bass will disappear. But that's true of any low wattage bass amp. It could have a bit more low end, but not a lot more at this wattage.
There's plenty of clean headroom; I can run a booster and get double the normal max volume and it's still clean. The transformers are more than adequate.
The wiring is simpler than on the models with the flip-top controls; this is only an issue if you replace the power cord.
If it's what's available, or you just love tubes (I do), it's a great practice amp, but it's no frills. There's no DI or speaker output, and it's fairly heavy, so it's not what you want for a small gigging amp.
Kalamazoo Bass 30 (combo, Late Version)
A mid-late 60s bass practice amp based on a push-pull 7591 circuit. Speakers are stacked vertically, front-loaded in sealed cab. There was a 50W