Mine is a pain in the arse. - You can lock the doors with it running, but as soon as the engine stops the central locking pulses and they unlock again; it took my ages to realise what was going on because I'd come back to the car and find it alarmed, but unlocked.
If you don't lock the doors you take your chance that the alarm will automatically arm an lock the doors when the timer stops.
Better to take it easy for the last minute or so of your drive, or just sit and let it idle for 30 seconds or so before you turn the engine off. - It's a water-cooled turbo anyway, so it doesn't really need a turbo timer.