Forget about numbers and the arguments over what constitutes an "active user".
Forget about the comparisons to Facebook.
When a new social service launches it is inevitable that the early adopters will predominantely focus on the service itself as they kick the tyres and attempt to find the lie of the land. As the service develops and more users join so features are fleshed out, it becomes more stable and the need to discuss it reduces - the conversation becomes less "meta".
This is exactly what has been happening on Google+ which could suggest it has reached that maturation point where users stop thinking about how to use the service and just use it!
Combine this with a period of relative quiet from Google - with regards to further integration with the rest of the ecosystem - and we have a period of calm and consolidation.
If we are to employ any objective measurement of Google+ then, perhaps, it should be this.
Image by debbietingzon.