Malcolm Barclay on 1-star reviews in the iOS App Store that reference incompatibilities with the iOS 5 beta:
Downloading & installing beta versions of iOS is akin to moving into a near-new house with missing windows, no carpet & some furnishing. In other words, it’s a building site. If you don’t understand this distinction, then you have no business installing it. You may not even be able to roll back to a prior iOS because of the firmware (software written directly to internal chip-sets) updates that will occur. You could brick your phone.
I can’t agree more. The problem is that these betas are so easily accessible and requires the user to do nothing to enable them. Technically you can only download it if you are registered developer, but the workarounds are relatively easy. Apple should do a better job of locking this down to prevent this kind of crap.
(via Daring Fireball)