The most advanced electronics related stuff I can do is changing a light bulb.
That is useful too.
Basically, this thing lets you see what is really going on in the circuit by plotting a graph of voltage changing over time. Quite similar to CRT TVs in that the beam scans horizontally at constant speed, then jumps back to the left. What is different, though, is that vertical position of the beam is driven by input signal and the rate of scan could be varied in very wide margins (from 10 seconds to 10 microseconds, in this case) and is synced to the input signal. This is *much* faster than a TV could move its beam, so CRT oscilloscopes used electrostatic plates instead of magnetic coils to drive the beam. The tube also has much lower voltage than the TVs, and much less brightness, only enough for one relatively bright line.
Of course modern oscilloscopes are just mini-computers with specialized input hardware to capture voltage graphs.
bought sometime in the 80s, much smaller
It seems that the transition from 70s to 80s brought much smaller, shorter CRTs. Oscilloscopes just a decade younger are all compact things with small square screens.
and with slightly fewer settings though.
This one is designed to do many extra tricks. It provides reference signal for calibration so that you can use it as as a quite precise voltmeter. It supports plates driven by external source or shorted (the chicken beak handles at the top corners). It supports synchronizing from an external source separate from the input signal, and it supports brightness modulation by external source.
Not to mention it has DC input (meaning you can measure constant voltage with it) which is quite a feat for a tube amplifier.
He used it to design some circuitboards and play around with some computers
Hell yeah!
P.S. Of course with oscilloscope prices beginning at $300 and just one pet project planned where I *really* need one, this old beast is a life-saver.