Installing iPhone iOS4 on my iPhone 3G and it was a big mistake for me. My iPhone instantly changed from a lovely, responsive device, to one that was taking 15-20 seconds to start up the SMS or Mail applications.
The list of issues I had with iOS4 was long and uncomfortable enough to force me into deciding to rollback to iOS3.
- Slow to start applications
- Applications are generally slow and unresponsive
- Camera app was slow to start, and slow to take a picture
- 3G network access became unreliable
- Lockups and freezing requiring restarts
It was slow and buggy enough that I hated using my phone at all. I didn't get this phone to become the owner of a useless brick.
Waiting for the first update to iOS4 seemed like a lame idea. Who knows how many of the issues would be addressed anyway?
iTunes won't directly allow you to rollback to a previous OS just by choosing a backup that was on that OS version. It doesn't downgrade the operating system, it only restores the data.
Trying to restore an earlier firmware explicitly in iTunes got close, but also failed.
After restoring the earlier firmware you will receive an error message telling you the OS could not be restored and you should choose one of your backups to restore from. Running RecBoot at this point in time allows you to take you phone out of recovery mode.... to find the firmware of your choice running.
You can then restore your data or setup for a new phone.
Guess what? My iPhone 3G is fast again. I'll be researching very cautiously before attempting another upgrade to iOS4.