The web client was a big success with the initial release of Dynamics NAV 2013. With Dynamics NAV 2013 R2 Microsoft has continued the development of the web client to include most, if not all, of the functionality available with the standard Windows client or RTC.
In order for users to have the same experience across all clients the Client Extensibility features from NAV 2009 have been dramatically improved upon. Previously we could only use client extensibility code on the Windows client and it had to be installed on every machine. Data display was limited to .NET / Windows Forms, or Windows Presentation Foundation forms with certain work arounds. Now with Dynamics NAV 2013 R2 we have the ability to use Javascript and HTML5 and we don't have to install it anywhere except the server. We can even use our add-ins on List pages. This continues the trend of introducing NAV to those outside of the NAV world and opens up a world of possibilities. This is the area in which I think the next big innovations will come and I truly hope to see more companies begin to take advantage of it.
These changes drive home what I love about Microsoft's current direction: interface standardization. I come from an educational technology / interface design background and the number one complaint I always hear about software is "It's too hard to figure out!!" The first step to making software easier is to allow users to instinctively learn from other software, to easily move from application to application. Microsoft is nudging developers in the right direction which will do nothing but make better software and happier customers in the long run.