What we have here is a classic StandAlone Complex with all the mobile OS developers. I have to admit that iOS5 is very exciting and will bring a lot of functionality to iDevices. That said, it's not that any real innovation is happening besides the consolidation of Apple's view to a more "cloud"/control-centric centralized data center methodology in order to control the user experience which I view to be VERY necessary.
Google's Android had attempted to control the user experience ever since Android 2.0. This however caused problems with their expansion strategy and hence, we have multiple devices with multiple customizations of the Android OS. With the plethora of Android devices available now, it's a crapshoot what OS you get with the purchase of your device. You normally have to refer back to expertly designed ROM packages from sources such as XDA-Devs. The user experience is incomplete with so many different variations. We saw this with Windows Mobile which is now Windows Phone.
iOS5 has a lot of borrowed features from Windows Mobile, Android, and even HTC Sense. The notification center is a straight throwback to Android OS which has been proven to be very efficient and effective. That's just awesome. Apple users let Google Android users test the tech before adopting it.
PC Free was an Android and Windows Mobile feature that was great. Android and Windows Mobile can run completely independently from a PC. Is it useful? You betcha! Were Android and Windows Mobile slightly flawed in this method? You betcha! Without a "cloud"-based synchronization method, it just wasn't realistic. Exchange server did this for Android and Windows Mobile very well for just E-mail, Contacts, and Calendar. iCloud can do virtually the same but the implementation may be different. If Apple doesn't have a universal backup/transfer method for Windows and Mac users, iCloud will be problematic. The synchronization method for iCloud must also be completely smooth like Exchange synchronization. Again, it remains to be seen if Apple can really pull this off. If iCloud works well, their gamble will pay off and we will see even larger adoption of iOS devices. Is iCloud a great concept? Yes, definitely! It integrates basic Exchange server synchronization with document synchronization like Dropbox but application specific, and it also will manage 3rd party application, book, and music sync. It's like the holy grail of synchronization.
iMessage is something I'm really excited about since BBM is my mortal enemy. BBM encompasses everything that is wrong with the corporate world. It's the back-end chat client on BB devices that goes around eDiscovery services in Exchange e-mail and other security messaging clients. BBM may be the catalyst for a lot of the financial crisis woes that happened in 2008. With logged messaging from iMessage, I think we'll see much more smooth messaging but also responsible archiving of conversations by Apple. This would really make messaging much more friendly if they execute correctly and it would also get me off of my Skype account for messaging.
Overall, I think the changes to iOS in iOS5 are really the way to go for post-pc computing. I already know that I'll be using the iPad and iPhone more for most of my computing needs since they are faster and easier than booting a Mac and then working off of it. Thanks to anyone reading this since I'm just ranting on what my opinions are of iOS5 with all of it's new advancements. While I do think that almost all these advancements come from other OSs, I think the iOS user experience is what really matters at the end of the day.