Google+ is okay if you dislike using different accounts for different purposes. With Google+, a single account allows you to use gmail, youtube, gtalk, and basically anything from Google.

I agree with this comment, and it's mostly why I chose to opt into G+ myself. I think the user base for both are very different even though they probably also have their fair share of users who utilize both, and it certainly seems worth it to have a voice in as many of these venues as possible. It's also probably why every blog or website have both on their share widgets, and seeing as most haven't chosen to drop G+ leads me to believe that it at least is somewhat effective, albeit still a lot far behind from FB judging from the activity statistics.
From a marketing perspective Google+ is a useful tool. First of all because it's owned by Google and Google loves promoting itself (see the recent storm regarding the integration of G+ in Youtube's comment system) and secondly because all marketing is good marketing. It's far from Facebook in terms of popularity / traffic and the aggressive promotion is annoying but more and more business owners/webmasters are turning to it or at least giving it a shot.
Personally, I don't like one bit the whole "one account for everything" phone verification deal and I find it intrusive, but I still use G+ to market my websites.
Since Google is king in the search industry, to play safe it would be good for you to use G+ because Google is trying to grow their social network and they might reward you in type if you use G+. I've heard that:
Of course you'll hear denials but that's the fact. But then it's more about reach than rankings. Some people who may find your stuff on G+ may not be on FB, Twitter or find your content directly on your blog because maybe they've never heard of it. So it's important to use every marketing tool available Google Plus being just one among many. . .Google+ activity has become a factor on search rankings, which is why it's a good idea to have a Google+ account and to create a certain amount of interactivity.
I've dabbled in it and will completely flesh out my profile soon. None of my personal contacts use it. I agree that it has a different atmosphere, and I'm hoping it will pick up in popularity so we small businesses can get away from the bad changes Facebook continues to make.
Using Google + will be a huge benefit in promoting your business because 1. It's a Google product, and they favor their products in search results and 2. It's fairly new so you have a fresh place to make a name for yourself.
I just bought the new Google chrome notebook by Samsung and am navigating my way around the whole Google atmosphere. There is a whole new world out there and I am excited to adventure into it. I have however found it very aggravating that on Google profiles you can't make one for a business yet and so then you have your name on everything..... I don't think Google Pages is popular enough to mess with much, but I am just now diving into it. I have heard that Google will be upgrading for people to make business profiles soon! Go Google! LOL