Started playing around with it on Friday (bit late to the party) and so far I'm really enjoying it. The circles are more or less a feature that Facebook really missed out on, and the individual privacy settings for every element are great. I'm also liking the ability to multi-sort people into groups so that, for example, I can quickly post to various circles during trips to organize just the people who live there. It's just more logical than having a big list of "friends" who are really just people you once knew in high school.

Also noticed the "local" stream (appears android only?) and thought it fairly useful for when you are somewhere and need advice like "where's a good place to eat". It seems like an interesting concept to be able to make individual posts public to the web for things like that or for events/fundraisers/etc but not have to select whether or not all posts are. +1 for that!

I'm still not terribly keen on the Picasa integration, because I have a fair number of pictures semi-private that I don't want to specify who to share with but don't want open to everyone. On the other hand, it's beyond handy that they decided pictures below a certain size don't count anymore and I gained 90% of my picasa storage back. And I guess that once it does get a bit more mainstream this functionality may be easier. I also had a problem with the fact that it forces you to share picasa albums during the app install and then manually disable them.

Had a few issues with the Android app where it constantly seemed to be firing up my GPS, which was a bit of an issue for battery life, but that seems to not have as much of an effect as I thought. That or it's stopped somehow.

Overall, this is absolutely going to replace FB for me because of the much better privacy and features and (yes, Google owns my soul) integration with pretty much everything else that I use regularly. This week's job, shooting invites to people who will be the most likely to populate my circles.