As I've been travelling around Australia showing some of the capabilities of Windows Server 2012 R2, one of the areas of interest to many attendees are the Hyper-V Replica features. To start, it's best to cover off what was improved between Windows Server 2012 and Windows Server 2012 R2 in regards to Hyper-V Replica.
The main improvements were as follows:
Flexibility in replication frequency - you can now replicate in 30 second, 5 minute or 15 minute intervals instead of only offering 5 minute intervals. This allows for either more up to date replications if bandwidth permits, or the ability to update less frequently.
24 recovery points - this was previously a maximum of 16, which now translates into 24 hours of recovery points to work with. There has also been a change in the way that the remote copies are updated, which is less disk intensive than the VSS method used previously.
Extended Replication - There is now the option to have a second replica, effectively giving you a third Hyper-V server or even a third site to replicate your VMs to. Where this gets interesting for Microsoft partners is that you could potentially offer this as a further level of data recovery to your customers from your own environment or from a hosting provider, so the customer has the ability to get up and running again from a remote location.
There are many other new Hyper-V features that were introduced, if you want to take a look at them the TechNet page is here https://technet.microsoft.com/en-us/library/dn282278.aspx