Hmm. Despite initially being dubious of it, I've found Siri to be quite handy sometimes, especially for handsfree use.
e.g. If I'm walking home from work, & have my earphones in, I can press the button on the earphones and dictate a text message to my wife, e.g. "Ask my wife what should I get for dinner?". I think you can get it to remind you to do things when you reach a certain location too, e.g. once you get home or get to work.
I just used it now to create a dental appointment in my calendar. Easier than going through it manually using the screen.
Anyway...
Microsoft has - rather bizarrely IMO - released a few big apps on iOS recently -
Last week:
My Xbox LIVE
Yesterday:
OneNote
Today:
SkyDrive
Today:
Kinectimals