I did and it's NOT an upgrade... they changed all the icons and a lot of behaviour - the feel of the device is quite different (some good but some not). Minor hates like email now showing how many in the inbox above the icon and not unread... so that damn nbrs stays there.
Do a full backup if you want to go back (you also need to upgrade itunes).
The overdrive app is completely dead, so if you get ebooks from the library, you should not upgrade until that's fixed. Very annoying, since I was in the middle of a book...
Otherwise, everything seems to work. I'm neither here nor there about how it looks, but it's worth upgrading to get the new control center, which is pretty useful.
Facetime now has a voice only mode, which could be useful if you want to save bandwidth on facetime calls. I have limited data and unlimited voice, so this isn't useful for me, but I could see this being useful for a lot of people.
Overall, it takes a lot of getting used to. Some things are click when you learn them, but are not obvious. And the flat icons can be hard to locate.
What I really like:
* The Control Center is easy to get to
* Folders can have pages of apps, this really reduced clutter for my screens
* Siri feels much improved
* A lot of third party apps are jumping on the flat bandwagon, which gives the overall experience more consistency
What I don't like:
* The multi tasking interface is a giant step backwards
* Safari feels much less usable on the iPhone, but about the same on the iPad
* The animations make everything feel sluggish
I've updated all my eligible devices. No problems as of yet on an iPad 2, iPhone 4, iPod Touch 5. I still like CanOpener (much better sound quality) for my music player, but other than that, I like the update.
I did... Can't say I am impressed. Most things work differently. Which doesn't mean badly, but why? I suddenly did not know how to do simple things like shut down apps, change screen brightness, etc.
One review mentioned that the interface is closer to android. Nice.... The icons and virtual keyboard look more toy-like to me.
Overall it works, seems stable, still hasn't fixed the drop down menu issues with DPC and other sites. Would have been nice if they had spent their development dollars on that, as opposed to a faux 3D effect of the desktop. (Had to read about it before I noticed it. Money not well spent IMHO.). But, like everything else Apple, you will have to adopt sooner or later.
Battery life seems to be going a little quicker on my iPad 4. But I haven't clocked it, so it is just impression, not science.
So far, mostly minor irritants. Nothing I hate, and once the changes are second nature, it will be ok.
I upgraded my iphone 4s and ipad 2 as soon as I could - I have a handful of apps for sale on the app store and wanted to see if any were broken by the upgrade (none were - whew).
Accessing some settings are a whole lot easier now (airplane mode, wi-fi settings, etc.). Search is easier to reach, but its not near as intuitive to find.
I have found a handful of apps I use to be broken, but updates seem to be rolling out at a fairly quick basis.
Bottom line, the icons are going to take some getting used to, but it is what it is. I don't see any reason to hold back from upgrading, but I don't see a whole lot of advantages in the new IOS for older devices. A lot of the benefit is for the 5 and and new (or upcoming) iphones and iPads.
I did not update my 4S to ios7. I was told it would run slightly slower under ios7. I have ordered a new 5S, which will come with ios7 in late October. I'll assess after that.
