According to Stone Temple Consulting who did a before Mobilegeddon and after (April 17, 2015) in Google Search Rankings there is a significant drop in Google Search rankings for websites that aren’t mobilefriendly. See post below for the comments on how they did the study.
What does that mean for you?
What does your website look like on a mobile phone? Does it respond and decrease in size to fit the phone screen or do you have to scroll to see all of the blog post? If you have to scroll then you don’t have a mobile responsive screen and you should consider getting a new theme!