I've been on blood presure medication for years--ever since the iMall days. Recently, with the holidays and all, I'd let my prescription get too close to needing refilling. On top of that, I was due to get the prescription renewed from my doctor. And on top of that, I was headed out of towm. I hurried to the doctor Wednesday afternoon but he wasn't there to just take care of it. They said they'd leave him a note to call in the prescription the next day. Uh huh. I anticipated a day of missed calls and the hassle of coordinating it all so I could pick up the prescription on Saturday.
Thursday morning, I got a text from Wal-Mart telling me my prescription was ready to be picked up. Wow! I'd forgotten I'd signed up for their alerts.
My feeling of being hassled trying to get my prescription refilled in time contrasted sharply with the peace of mind I felt upon getting that text. They were night and day. That text let me know, in as long as it took to read it, that everything was fine and I could relax.
This is a small example, but it illustrates with great clarity the power of event-based interactions over a request-response model. Constantly checking to see if something has happened or has changed is a pain. A simple alert system fixes all of that. Request-response systems aren't going away--they're too valuable, but evented models fit so much more cleanly with how our lives really work.