In my books, Google's been a bit funky in the last few months. Intentionally changing the way page titles are displayed in their SERPs, heavily pushing Google Authorship to cut back on spam guest blogging, and now introducing a way to incorporate reviews aside from their own in their SERPs. Although the degree at which the reviews or co-citations from these sites will increase your positioning in Google or other search engines, you can bet you'll be seeing reviews from these sites next to your website if you're able to get them. With that in mind, here are a few locations I would strongly recommend getting reviews from whenever you can.
Google Plus gets the top spot as it is by far the most important place to get reviews for your business, as it's Google's baby that it will never abandon, and it will always be Google's most trusted source when it comes to reviews for your business. It also seems that Google will continue heading in a direction of quality is more than quantity, and they will hold a much higher regard for sites that have a few reviews from individuals that have a high level of activity with their own Google Plus profiles and are in a high number of circles of other individuals that do the same thing. Sites that get plenty of "outstanding" reviews from irrelevant individuals or people that have no other activities than posting reviews to sites will have little value, and I'm sure they will be the targets in future Google quality updates.
Google makes setting up a Google Plus business page is currently fairly simple, but I won't go into the specific details as Google will most likely change things again in a month or two. One messy but important aspect to note is that if you have multiple locations, you should set up individual locations for them in Google Places, which can get their own reviews. Once everything is set up, it won't take long before it begins to display alongside your website for branded search queries, which will give users the option to write a review for your business if they so desire.
Other Review Sites
Aside from Google Plus, here are six other review sites that Google has been factoring into their SERPs.
These are just a few that I've noticed personally, and I would strongly recommend setting up listings on other local review sites if you're able to find relevant ones. I would only go for free ones for now, as Google hasn't shown any preference for reviews from websites where you have to pay to be listed. It's more important than ever to get these set up properly as soon as you can so potential customers have more ways to find your website. Finding ways to actually get quality reviews and to cut back on bad reviews is an entirely different post, but it all starts by building the foundation of your online presence and prove to Google that you are a real business that has customers that care enough to post content about you.
I can't stress this enough for all you black hatters out there; don't get fake reviews. You may be able to get away with it now while Google is still ironing out all the wrinkles in their local search algorithm, but it will come back to bite you in their future updates when half of your reviews for your local service come from individuals on the other side of the world. Good luck figuring out a way to remove those reviews then!
A Note on Bad Reviews
It's important to note that most people who write reviews for businesses are either really happy with the business, associated with it, or had a terrible experience. It's normal to get bad reviews, and it looks more natural to search engines as well. If you can, with any negative customer or user experience, follow up with them if possible and see if there's a way to rectify the problem they had.