Ack! I just decided to try figuring out and using Twitter this week and then Google+ comes along. Who has time for all these sites and why can't everything just happen in one place.
I'm thinking that if Google+ is successful, it will take the best of FB and the best of Twitter and merge them into one beautiful site. I have high hopes after playing around with it a bit, but only time will tell if it is adopted by enough people to become successful.
(As an aside -- circles are awesome. Don't you agree?)