During a heavily attended session at Visual Studio Live! 2013 Las Vegas last week, Brian Noyes attempted to clear up some of the confusion about where developers should focus their efforts in the crowded field of Microsoft technologies. Noyes, a Microsoft regional director and MVP, and CTO and architect at Solliance, counseled that developers should primarily consider their users and those users' needs when choosing a technology path.
Don't put logic on the client side unless you have to. Put things behind the service boundary...You can't think just in terms of the UI.