Vijay in the Microsoft Release Management product group has provided a nice post on the various methods you can use to migrate from the earlier versions of Release management to the new one in Visual Studio Team Services.
An area where you will find the biggest change in technology is when moving from on premises agent based releases to the new VSTS PowerShell based system. To help in this process the ALM Rangers have produced a command line tool to migrate assets from RM server to VSTS, it exports all your activities as PowerShell scripts that are easy to re-use in a vNext Release Management process, or in Visual Studio Team Services’ Release tooling.
So if you are using agent based releases, why not have a look at the tools and see how easy it makes to migrate your process to newer tooling.