It's a cool gadget but the problem is the competition is also offering the same features: 10Hz precision gps with a live leaderboard of best times, even sorted by brand (best VW, Audi, BMW 0-60mph, 0-100kmh, 100-200km/h) at half the price, so it is kind of hard to justify the extra cash unless you absolutely need video overlay of the dials which is (I think) the only exclusive P600 feature.
Update: Competition also offers the video overlay, so basically just the same.