One problem, though, is that you have to have the right email address for the contact. For example, there are a lot of people in the contacts Google+ imported from Hotmail who actually have Google+ accounts already. But, because the email address I have associated with that person in my Hotmail contacts is not the email address they use for their Google+ profile, they don't show up that way.
I don't have any comprehensive way to know which of my contacts are already on Google+ and which aren't, though. I decided to just drag the contacts I have into a Circle, so they'll get an email when I post to that Circle. If they already have Google+ profile at a different email address, hopefully they'll let me know.
The first time I dragged a contact into a Circle, Google+ displayed a pop-up message explaining some of the ground rules of Circle etiquette. The contact will appear on my public profile page--meaning others will be able to see that the contact is in my Circles. I can change that behavior to hide my contacts if I choose.
The message explains that by adding the contact to a Circle, the contact will see the updates I share with that Circle, and I will be able to see whatever information the contact chooses to share with me. More importantly, it describes what the contact will see. It says the contact will be notified that I have added them to a Circle, but the contact will not know the name of the Circle(s) I add them to.
Why is that important? Well, it can be a sensitive issue if I put someone in "Acquaintances" who feels they should be part of the "Close Friends" circle. Or, if there is someone I don't really want to communicate with on Google+, removing them from Google+ entirely would be too obviously confrontational, I can create a Circle called "JerkFace" and stick him in there.
It is still difficult for me to go through my contacts and compartmentalize them in that way. Some are obviously "Friends", and some are obviously "Acquaintances", but there are a vast number of contacts that occupy the gray area between the two and make it difficult to assign them. I feel guilty enough for assigning labels to my personal relationships in that way. I don't need to also deal with the backlash that would occur if the contacts could also see what Circle(s) I put them in.
More Like a Venn Diagram
One thing about Circles, though, is that there is overlap. For example, what if my best friend or cousin works with me? They would have to go into the work and friend or family Circles. What if a co-worker is also on my team in the golf league? That person would need to be in both the work and golf league Circles.
Conceptually, this still makes sense to me. In fact, I already manage my contacts on my iPhone and iPad using a similar concept in the VIPOrbit app--they're just called Orbits instead of Circles. Being able to put a contact into more than one Circle has benefits, but it can also have some inadvertently negative consequences. We'll cover that another day, though.