- Google+ has no cachet... it's not really that cool to be on Google+... there is no reason to right now (as opposed to just being on Facebook). Google tried to make some buzz with the "fake" limits on user growth, but those in the know, know that was contrived.
- Google + doesn't help companies (yet). I expect Google will get around to it, and when that happens, companies will rush to setup their pages... but soon they will realize: it's EXPENSIVE to maintain Google+, Facebook, and Twitter: then they'll say, gee, we've invested in Facebook; we're staying.
- Games will kill it. Games on Google+ are coming, and when they do, let the spam wars begin. Google has a TON of work, trial, and error to do, to keep up with Facebook on this delicate balance of fun and non-annoyance.
- Google+ doesn't "give me more" of anything over Facebook. It's just not superior in any way; so what's the point?
- Google Adwords is too expensive; and Google+ may "dilute" prices over time for adwords (which Google WILL NOT LIKE). Hence, the quick, fast, and early demise of Google+.
Google. Stick to search! It's making you rich!