I've used my iPad2 for almost 100hrs and on over 3000nm long cross country trips. I have had one "unable to find fix" in all this time and it lasted for less than 2 minutes. It consistently delivers 10m accuracy, often less than 5m. I did buy a BadElf external GPS that plugs in to the charging socket, but don't use it much as I can't charge through it (the charger provided blew up on 24V, of course).
The iPad2 and Foreflight here in the US has literally changed my life. It's the best thing ever.