Bought it and playing it (a couple of hours so far). It's certainly NOT for the action-minded but for the true-blue mechanics as every twist of a bolt is essentially simulated. All of the 'action' takes place in a bomb-proof berm area at an airfield with barrage balloons and Spitfires flying by. You have to work up to Spitfires and earn your Aircraftsman rank. All of my work has been on a Tiger Moth so far. The graphics are on a par with CloD and I see a possibility to blend the two games (if only via a custom movie). I'm working up to Leading Aircraftsman. I have done everything from fuel/oil top-ups, undercarriage replacement (including tail-skid), removed rockerbars, valves, rods, camshafts, sparkplugs, piston rings, replaced a propeller and even patched a couple of bullet holes.
I can honestly say I have stripped a Tiger Moth engine all the way down to the piston rings (and replaced them), LOL. It can be a bit tedious but I'm not a mechanic and am learning about engines as I go along. As I said, it's definitely not for the action-oriented but if you are curious about some of the work required for aircraft and have patience you can actually enjoy this from a learning point of view.
I should note that I'm using Beginner mode (non-expert) and there are 'highlighted' hints. To sum up: a nice relaxing game so far but the Tiger Moth's engine is pretty basic I can only imagine what the Spitfire engine will be like.