Dude, if you have a Gmail account you have a G+ account. They may technically have 170m users. However, .00001% of those are active users.
link1.13 percent of Twitter users update their accounts more than 10 times a day. About 85.4 percent of Twitter members tweet zero times a day and about 6.5 percent tweet once a day.
If Google's intention is to push content, they're not doing too badly when compared to the only other service that is even remotely comparable.
Also, https://plus.google.com/explore -- look at it. How is it different than Facebook? It doesn't have the shit-ass "LOOK AT MAH BABEH" posts. The shit that shows up there is from major content producers. This concept (content delivery) is what G+ is after, not announcements (Twitter), not your personal story (Facebook).