Ah Google: we LOVE your search engine, but a lot of us struggle with your social media platform!
Google Plus is an essential part of your social media offering: you NEED to be on it because if you're not then the evidence shows that your Google Search ranking can be affected. Even if you update it just once a week, it's worth it.
And Google Plus is changing: they themselves admit that it's a bit clunky and really, we've found that more time and effort is worth investing in Facebook and Twitter because that's where everyone else is!
But it IS a must and it is useful: there are lots of aspects to Google including maps, that are important to be on. So get on there and have a presence.