Has anyone used this app and if so what do you think of it?

http://www.gps-laptimer.de/Home.html

Sorry, cant answer your question, but have you seen the hall of shame on the website?

I used it a couple of times. It works well as a basic logger and I think it is worth it for the £7.99 (I think when I got it) to get some data. I changed my phone to an Android which you cant get it for otherwise I probably would of got it again.

I now use Trackmaster which overall I think is a better laptimer.

There are quite good free ones on the market so give them a go. Not used any of them on track but basic recording and logging seems impressive for no cost.

I bought the full version and its very good, unfortunatly the iPhone is limited to what track loggers you can get. Just make sure the GPS signal is in the green and you'll have no problems . All updates and all the tracks are free. As far as I know It does everything track master does like logging speeds, cornering and braking forces, intermediate and even now ghost laps! If you can position your phone to use the camera it will overlay current speed, time and give a little G-meter if thats your kind of thing :-) As bizzle has found get yourself a separate Bluetooth GPS device as the iPhone is only 0.5 hz so speeds and exact positioning is limited.

Thanks all for your replies. Not so brilliant as a stand alone device then.

its 'ok' i guess. when i used it at bedford i didnt manage to get one decent recorded lap. at brandshatch it recorded every lap! its the best you can get for the iphone though. my next phone will be an andriod based device so ill be using trackmaster :-)