For many years my definitive address book and diary have resided on my computer. I really can't remember when I last used one of those paper things. The problem with this was that when I was out at a meeting, I couldn't check my diary, so had to cross my fingers and hope, if necessary ringing up to modify an appointment later.
Since having the iPhone (and more recently the iPad) things had improved significantly, because every time I synchronized my mobile devices they got up-to-date copies of diary and address book, so when I was out and about I had access to these crucial resources. They might be a touch out of date, but essentially it was all there. What's more I now had extra backups of this essential data - and unlike users of a mobile phone with a conventional, unsynchronized address book I would never lose my phone numbers.
In the last week, Apple has launched iCloud, and with it my situation has changed again - and more fundamentally than I first thought. The migration was not without a little pain. When the Apple software was attempting to set things up, its duplication correction module went beserk, so now every entry in my diary is in twice and several people in my address book have two copies of their address.
What's more, the process has partially screwed up my desktop control centre, Outlook. It has moved my address book and diary to one hosted on iCloud, patched through to the Outlook system. Outlook is designed to be able to incorporate external sources, but it very much regards them as 'the rest' rather than the main one. So several of Outlook's useful features, like displaying the next six diary entries on the home screen and being able to add flags to emails to put them on your to do list have stopped working.
But in return I have a more fundamental change then I realized. Up to now, mentally, my 'real' address book and diary have been on the PC. So if I want to look up an address I would use the PC, even though it's a bit clumsy. Now my 'real' address book is in iCloud, so my natural tendency has moved to use either the iPad or the iPhone - and that's quite a fundamental shift. (It also means I can see my diary and address book from any internet connected computer, but the times I'm likely to use this seem very small.)
This is a significant shift of mindset, which I simply hadn't realized would come with the process. It will be interesting to see how things evolve...