I've recorded around 2 hours of audio in the audio recording app several different times. I'm pretty sure they are correct above, it's only limited by your storage.
I will say that one time when I recorded I was unable to sync my iPhone until I restored. I don't remember the exact error but it said something like the data on my iPhone was corrupt and I'd have to restore. iTunes could not read or write to the iPhone, but the iPhone worked fine. Syncing was fine before I recorded and corrupt immediately after. A restore fixed it but I lost that 2-hour concert recording.