Everything is similar like gmail service but there are some drawback are as follows:
Annoying advertising in email service .
not user friendly.
needs to click on option, because back option is not working like gmail service.
Good Things:
Good user interface for Cloud service than gmail.
Provide more option like excel, word, .etc that is document service.
better video calling service skype than gmail hangout .
there is new option flow it is part of Office 366.
it combines many services like twitter, instagram, SQL and many more