So, now that G+ has had some time to sink in... I don't use it and I still go to Facebook. Why? Everyone's still on FB
I doubt this is likely to change unless G+ offers something that FB lacks, otherwise with two equally featured apps I'll pick the one that others use (sort of a key feature for social networking). I'm willing to say that it's too early to say for sure that G+ is a failed venture but at this point it seems very much like Euro Disney (open for business but nobody showed up)