Let's go through the top new features of SharePoint 2013.

Authorization (Claims-based Authentication in SharePoint 2013)

  1. Classic Based Authentication

    • We cannot configure the Forms basedauthentication, if our web application is using Classic Mode Authentication. We can convert a web application from Classic Mode Authentication to Claims-based Authentication. However, that can only be done using PowerShell commands and it's an irreversible process
    • Classic authentication supports authentication types like Kerberos, NTLM, anonymous
    • Classic is more commonly seen in 2007 environments
  2. Claim Based Authentication

    • It enables authentication from Windows as well as non-Windows based systems. This also provides the capability to have multiple authentications in a single URL
    • Claims-based authentication uses claims identities against an against a trusted identity provider
    • Claims are the recommended path for new deployments in SharePoint 2010

Search

Continuous crawl (making new content appear in search results that are much faster compared to SharePoint 2010):

SharePoint Store

Social Integration feature is more advanced compare to SP 2010

Full Cross-browser Functionality

Workflow Integration with Workflow Manager

Simplified Document Management

Office Web apps are free (and work on mobile devices)

Improved Publishing Capabilities via Cross-Site Publishing

Offline and Sync of My Site (and other libraries)

References:

What's new for developers in SharePoint 2013

Summary

In this article, I've explored the SharePoint 2013 new features that I like most.