Note the new layout and updated views. I believe it's a nice evolution of the Web Browser experience. Further if you use Firefox or Safari you too can use the Premium version of OWA now - you won't be subjected to the Light version. Good news!
Take a look at the Options screen:
You can immediately see a new feature to connect Outlook to your account - a great idea (and about time :-) )
Clicking on Groups shows the Groups you belong too and the Groups you own. Notice you can request to join _and_ leave groups
And finally if you're an Administrator you can manage your Org to a certain extent through the ECP. Note I have changed the 'Select what to manage' setting in the top left corner to 'my organisation'. You can see I can add Users, Groups and Contacts, and also delete them if I so choose. I am also able to perform Message Tracking from here.