Originally on the home screen (or what would be like the desktop on a PC), you could file your apps into folders. . . but the folders maxed out at I think 6 or 9 apps. So, if you have more than that amount of say, games, on your phone, you had to make a second folder to accommodate them. Now, you can put as many apps as you want in each folder.
I have an Iphone 4S. I upgraded yesterday and had some issues with Facetime and iMessage that caused me to have to erase my device and reinstall everything. With iCloud the process was fairly painless, although I will have to reload a bunch of music. (I’m actually not upset by this as it forced me to go through and rethink a bunch of playlists and add a bunch of new stuff that I never got around to adding.)
I thought it looked a little cartoony at first, although the new look has grown on me and I like it now. I changed my wall paper and that helped. I turned off the background app refresh as I’ve heard that it is a power drain. I also turned off the parallax effect just in case it has an effect on battery life.
I like the control center. I’m glad Apple added this as this makes my life easier since I switch bluetooth on in the car and switch it off whenever I get out of the car.
This. Easy access to the things in the control center are an absolute godsend. It also allowed me to delete my flashlight app, which was taking up valuable real estate on my front home page screen.
iPad 2 here.
iOS7 upgraded flawlessly here and it seems to run just fine.
All I have to really say about it is that it looks more like Android now.
I’m using is new interface in the iCloud website on my PC at work, and it’s horrible. Too bright, too pastel, the lines are too thin. I’m having a hard time seeing things. I’m amazed they would make a user interface this painful.
Thank Og for enlarging and bolding typeface controls.
I wish it could run Firefox.
Edit: An iPad.
What (s)he said.
Warning! Back up before you make the switch! My iPhone 5 crashed and burned (stuck in “recovery” mode) when I tried to upgrade to iOS 7. Notes, contacts, favorites, some photos (sniff!), a few apps…gone.
I learned the hard way that phones are just little computers. Now, I back up automatically to iCloud (with occasional manual backups to iTunes on laptop.)
As for iOS7 itself, it’s okay. Modest improvements all around, but nothing extraordinary.
My 4S battery is taking a beating with the new OS.
The new OS is nice, but the battery issue is just too much, and I have turned off any and all features that could drain it. 
Also back up after you make the switch. Keep backing up continuously. There is no reason not to.