How has the Visual Studio 2015 installer changed?
You can now select the type of development you'll be doing and install only the infrastructure necessary for that development. This means if you're only doing desktop (or web or mobile) you can select that option, and the installation completes much faster
For instance, the .NET desktop option provides support for WinForms, WPF, and console application, and the entire installation process takes about 15 minutes.
How does the selected installation help me?
The biggest benefit is that if you need configure VM’s to test certain scenarios, you can get them up and running much quicker. Also, if you need additional resources for another development technology, you can re-launch the installer and add on additional technologies (like ASP.NET, UWP and Xamarin) as you need them.