I always assume users haven't read the release notes, even if they say they have, and even if I'm sat behind them watching them read them 
But noted on maybe adding a chance to back out of a running pihole -up session before committing anything to disk.
The difficulty here, though, is that any new logic added to the update script is pulled by the initial update script.. so in order to get the new update message one needs to update.... starts to get a bit recursive!
Personally I've been using the docker image for the last few years - I'm least likely to get bitten by any surprises in newer versions, but at least if I do it is trivial to roll back to a previous known-working image.
I'd love to be able to do something similar for bare metal, but it's a bit more complex. Maybe by the time 7.0 or 8.0 rolls around...