I don't really like VPN-mode since Apps like to share identifiable information with their servers, ad services can track me and google knows it all anyway. There are apps that are browser aware and those should be used in combination with Orbot since they can switch to an anonymous mode, don't keep persistent data (cookie) and isolate interaction from other apps.
This mode only really protects your data coming through the network from your phone to router, e.g. open hotspot, but doesn't keep you anonymous.