Nothing exciting. Let me quantify this before I get shot by the Apple fanboys. I'm not a Microsoft fanboy either but I am not buying the hype and feature sheet.
Example:
1. iCloud. Have Windows Live ID and Live Mesh integration in windows for nearly 3 years now. Works across mobile devices already.
2. Messages. Windows Live Messenger has social integration already which is on par with this.
3. Reminders. Windows Live calendar does this and gives you alerts through windows live messenger and email.
4. Notes. NOTHING on this planet compares to Microsoft's OneNote.
5. Notification center. Windows live has one built in that you can integrate with. Oh and you also have the system tray.
6. Share sheets. Windows has had "sent to" since about 1996.
7. Twitter. Windows live integration.
8. Game center. We have shops for that and Steam and all sorts. It's an open market.
9. Airplay mirroring. Woo yay etc. Windows media player (!) does this with my Sony Bravia with no complaints. I can right click a video file and select "play on Bravia" and it appears on it straight away. This required NO CONFIGURATION and no special boxes. Both have wireless cards in them. No store or DRM available or required.
10. Gatekeeper. Windows firewall is actually on par with this and is an application AND/OR system level firewall. Microsoft security essentials is the rest.
11. Chinese features. Windows is the mainstream OS in china for a reason (i.e. excellent language support).
The only thing above that cost anything is Windows (which cost effectively nothing as it came with the PC) and OneNote (which cost me 200GBP) and included Word, Excel and Outlook as well. Oh and the nice Acer TimelineX machine only cost me 400GBP, TV cost 300GBP so total 900GBP
Compare that to a MacBook which cost more than that to start with at 999GBP.
Oh and I don't have to pay 99GBP to write software that works on it. Visual Studio is free.
Doesn't add up.
Hmm.