Contrary to what some might claim, almost nobody can use the slide rule when airborne.
What is one going to do with it??
The wind calculator side is useless unless you know the actual wind. One can use it backwards to work out the wind knowing one's heading, track, etc, but you won't know your track unless you have a GPS
in which case why work out the wind? It will be as much use as knowing yesterday's FTSE100.
The other side is just a straight multiply/divide slide rule, bent around into a circle. I used those at school in the 1960s. But a £5 calculator will do that job and with much less chance of an error. I do carry a calculator but, FWIW, in 10 years of flying I have never had to calculate anything when airborne, flying with a GPS. I use it only after a fill-up to check the fuel totaliser error against the pump.