When iOS4 was released earlier this week, it seemed like a no-brainer for iPhone 3GS, 3G and iPod touch owners to update: after all, free software and boosted features can't be argued with, right? Unfortunately for many users its turned out to be less impressive than expected, with some handsets now running sluggishly, battery life taking a significant dip and in general the whole experience being sub-par. Apple may well update iOS4 for these earlier devices and iron out some of the hassles, but until then Lifehacker has a handy guide for downgrading back to iOS 3.1.3.
Basically, it requires digging out a copy of iOS 3.1.3 - which is probably backed up on whatever computer you use with iTunes, but if not is available online - then using the regular firmware update tools and some third-party software called RecBoot to roll back from iOS4. It'll be handy if you have an old 3.1.3 backup from just before you updated to iOS4, too, since otherwise you won't be able to restore your apps back to the device.
User experiences with iOS4 on the 3GS, 3G and iPod touch are varying widely - some have faster devices and couldn't be happier, while others are cursing the new software - so your mileage may vary. Let us know how you get on (and whether you're sticking with iOS4 or downgrading) in the comments.