A few things I've noticed
-This really is PC Free. After iOS 5 is installed, it's all wireless if you want it to be. Of course, I had to download iTunes 10.5 to sync up my backed up iPhone info and I installed iOS 5 using the xCode developer app. The new initial user/phone setup is sleek. A couple questions, mostly getting your Wifi password, and a few other easy to set things, and you're all good to go. It asked you if you want to sync up using the cloud, iTunes or not at all when you first start the OS. For a new user, there's no need to touch iTunes or a Mac or PC if you don't want. Having WiFi would be a very good idea though!
-iCloud is turned on by default (you have option to turn off during setup) and backed up my stuff to the cloud (I have no idea how quick because it's done in the background) I tested out some iCloud stuff. Bought an app on my iMac and saw it available to be downloaded from iCloud on my iPhone right away. iCloud appears to be as simple as it was made out to be in the presentation.
-the new notifications system rocks. I know Android has had this feature but I've used Android's and Apples looks and feels smoother. This may be playing catch up to Android but it's very nice. Glad it's finally part of the main OS. Also, the new lock screen works as advertised. I received a Yahoo IM and saw it on my lock screen. Instead of swiping the normal unlock at the bottom of the phone, you swipe the icon of the notification and it opens the phone to that App and message. Again, not a new idea but it works very well and looks great.
If you haven't seen, iOS 5 is already jailbroken and someone (a 14 year old kid in Italy) has already released a wiget for the notification which allows you easy access to some important settings.
You can remove, and I did, the weather and stock widgets to remove clutter.
For the lock screen you can choose, per app, if you want the messages to show on the lock screen for privacy. Options for notification center and lock screen are separate for each app. You can choose 1, 5 or 10 messages to show per app.
-reminders app is pretty straight forward. I set a location note to remind me to go to Del Taco as soon as I leave the perimeter of my home to test it out!
-OS wide dictionary is nice too.
-new camera stuff works well. Easy to crop, get rid of red-eye etc right after taking picture or later. Another long overdue addition is using the volume buttons to snap pictures.
iOS 5 feels rock solid. I know there's plenty of bugs but this is something that could be released within a month. I think the only reason they're waiting until the Fall is to release it with a new iPhone.