What can I say, BRILLIANT! Warns of all mobile and fixed cameras including average speed cameras, is very accurate and will work in conjunction with an iPhone navigation app. Weekly database updates are prompted as you launch the app on the iPhone and downloading new data is quick and efficient over WiFi or 3G.
I had CamerAlert on my previous 3GS and it was brilliant then upgraded to 4S and had problems but the folks at CamerAlert support were brilliant and sorted it out for me; it just took some details and 30mins and then up and working perfectly. The app is fantastic but what’s even better is the support that you get when there’s a problem. 5 star Service.