Congrats. Mine was a '77, I really miss it.
The 550 is very versatile. It's not huge, so it is a great city bike. My typical MPG was the low/mid 40's and I broke 50 a couple of times on longer trips. And despite the small displacement, it hauled my 220+ pounds down the highway at 70-75 no problem. I rode it 1400+ miles around Lake Michigan during a leg of the 2011 World Tour (scroll down for info on this year's tour and try and participate, its a great time) and it never missed a beat.