Hmmm. Maybe it's a timing thing. I used it back in June and it was a doddle.
Dropped the car off at the Europcar terminal, walk into a near deserted terminal. Straight to the check in desk and received a hand written boarding card from the Air Southwest rep. Got the airport departure tax from the machine straight away, no problems although it would have been better if it asked you how many vouchers you wanted instead of doing it twice for the two of us (or did I miss it?). They should incorporate this into the ticket price, have more machines, be able to pay it on line, or have some machines in the arrivals area so you can pre-buy and save time.
Very jovial and friendly staff at security, only a few in the queue. Seating was ok inside. No Ryaniar flights so, probably why there wasn't a mad scrum for seats. Boarding was a bit strange being corralled into the waiting area by the gate for 10 mins before boarding, but hey, it's a small airport.
My flight was on a Friday afternon, well before the start of the school holdiay season. I try to avoid flying out of London City on a Friday evening as I know it's going to rammed with Eurosuits on their way home who think they are above the travelling tourist. I still do it, just to pi55 them off of course.