There are often preconceived ideas around what ADFS provides and whether it is required when you are moving to Office 365. The below points cover some common conversation that we have with customers.
The supported User Agent Strings for ADFS 3.0 by default do not support Single Sign-On from Third-Party browsers, i.e. Firefox and Chrome. To enable this functionality you can add additional supported User Agent Strings to the ADFS configuration.