Now that Google has finally updated their mobile browser display and is, after a very long hiatus, allowing users to leave reviews on Android and iOS mobile browsers, the question arises of how to best direct your customers to leave a review. What is the best link to share with them so that they can leave you a review?
In days past, giving them your Google+ URL, perhaps even your "custom Google+ URL," worked well on the desktop. If you appended the modifier "?hl=en&review=1" it would even automatically open the review box for the user. Some folks, in an effort to provide a mobile solution, did a Google+ Local search and presented that URL for users. Neither solution works any longer.
The simplest link you can provide now that works on both the desktop AND on most mobile browsers is a link to a search on Google that returns the Knowledge Panel for your business. Depending on a number of factors it could be something as simple as https://www.google.com/#q=barbara+oliver or if you have multiple locations in a given area something more specific like: https://www.google.com/search?q=uncle+bob's+8161+main+st+williamsville or https://www.google.com/search?q=uncle+bob%27s+(716)+632-7796.
It would appear that there is a bug in the presentation at Google and that if a location has NO reviews, then the mobile interface offers no opportunity to leave a review using the above URL. How weird is that.
This URL gets people to a search result with the link that says "Write a review" presented front and center on the desktop. In the case of mobile, it requires the user to be more proactive and click the "more info" icon and scroll several windows to get the area where it says "rate and review." Even though the mobile prompts are not totally obvious, it is significantly easier to leave a mobile review now than it has been for the past three years. Some worry that Google filters reviews based on the referral URL and if your URL takes a user directly to the review box to leave a review, that it is more likely to be filtered as a spammy review by them. If you are someone who does worry about that then this search based approach to generating a URL should alleviate your concerns.
Is there a single URL that will get users even closer to where they need to be? Yes!
It is now possible to use the link that results from clicking on the "write a review" choice and it will direct users to the listing AND automatically open the review box if they are logged in. If they are not logged in, it will request login and and then take the user to leave the review. And this link works on both the desktop and mobile and across every browser I have tried so far. It looks like: https://www.google.com/?gws_rd=ssl#q=Barbara+Oliver+&lrd=0x89d37487dfb1ea75:0x2daea2d3b6aa10c7,2. Essentially it is the query + the FID and a ",2" to open the review box. Note that the one time this link doesn't work and provides no messaging is if the searcher is using private browsing mode on the iPhone.
Update 1/6/16: With recent changes by Google the above link no longer works if the user isn't logged in. I would suggest using https://www.google.com/?gws_rd=ssl#q=Barbara+Oliver+&lrd=0x89d37487dfb1ea75:0x2daea2d3b6aa10c7,1 as the preferred link. It replaces the ",2" with a ",1" and then as some of the commenters noted using Google's URL shortener (goo.gl) to shorten it to something like: https://goo.gl/QhZdcZ. This works both logged in or not and takes the user to the review shadow box but requires that they click on the write a review link.
On mobile that link will take the user here:
It isn't difficult to generate the URL, but it seems -- at least on the Macintosh -- to require the use of Chrome and not Safari. Here are instructions: