Haven't used it for a BA flight but on a flight MEL-SYD earlier this year, we were flying Qantas and used the totally self service check in and bag drop. It was great! We first checked in then took our luggage and BP to the bag drop where it was weighed and questions answered, tag printed and then dropped into the conveyor. So quick. We were flying at a quiet time of day so maybe it's hell at busy periods but I enjoyed the experience.

I saw on LinkedIn that there are trials of improved bag drop technology starting in T3 LHR soon (or already under way). Not the same scale as Qantas but heading in that direction.