Had some issues before using the SharePoint REST API, well, actually using the jquery implementations. Been struggling with the basics to get user profile properties. Some methods and examples suggest you get the PeopleManager class, pass the user (which then differs from onsite to O365).
If you are just after the user profile info of the current logged in user (as I am), the REST API works great.
Example: Get all user’s properties
AND BAM, instant JSON result with all the info
Some great examples: