Between twitter and google+, I'd say google+ is the one with mass appeal. It's simply better for what people call "social" - sharing updates, sharing photos/albums, chat/conversations etc all within their own private social group.
PS: I don't even believe the current growth/engagement numbers coming out of twitter entirely. There's a lot more spammy accounts there than used to be that put out hundreds of tweets a day and I wonder if that's heavily padding twitter's user growth currently. Most of my current followers are "fake". Same with my friends who aren't particularly famous. The statistics don't reflect this properly.
I also think that SV peeps use twitter at a far higher percentage than the real world, leading to very skewed perceptions.
See where they are now?
There you have it
It may be easier for G+ to be used, and this is important, but Twitter has a more faithful following, and more specific uses