Cloudflare launched its 188.8.131.52 service in April as a bid to improve privacy and performance for desktop users, and now it's making that technology available to mobile users. The company has released 184.108.40.206 apps for Android and iOS that switch the DNS service on and off with a single button press. So long as it's on, it should be harder for your internet provider to track your web history, block sites or redirect traffic. You might also see performance improvements, particularly in areas where connections aren't particularly fast to begin with.
The service remains free, and there are pragmatic reasons for that. It not only serves as an advertising mechanism for Cloudflare, it potentially improves the performance of the sites themselves. There are certainly alternative DNS options, and this is merely one part of a larger security strategy. However, this might be the most accessible solution of the bunch -- you don't have to know the first thing about domain names or ISP tracking to see a difference.