I really haven't tried it yet, but it is very popular with the younger set.
I don't think I would be too happy with things hanging off me (like a messenger bag).
But -
I bought this little Honda CB200 that I hope to do some of my commuting on. Â Since it will eventually be finished in the cafe style, it won't have saddlebags.
Then I stumbled upon this handy backpack, made for motorcyclists, and at a very reasonable price. Â I got one last Spring, and I was just checking it out. Â Very nice. Â Their description fits it well. Â Unfortunately, for me, mine doesn't have the red stripe as pictured, just a blank panel there.
http://www.icu-ucme.com/shop1.phpIt is the last item on the page.  £14.89 or $24.13 at the current rate.
Last 10 April, I paid £14.84 or $22.33, which included shipping, as those figures are from my PayPal account history.
I thought some of the folks here that ride with no saddlebags might be interested. And it's a price that is easy to get along with!
Still, remember to ride like you are invisible.