Good reason for a 5 to 5.1 upgrade

We are currently running one ESXi v5 update 1a host (vSphere Essentials) and are not experiencing any problems. My usual assessment when it comes to upgrades is "If it ain't broke, don't fix it!".

Is there any real reason (performance, features, etc.) to rock the boat with an upgrade to 5.1?

Note, we are using Veeam Essentials (latest v6.5); no problems with backup either.

Thanks in advance...