It contains all of the previously released post HRP 1 hotfixes for XenApp 6.5. Very important to know is that it is a beta, and completely unsupported. You should only install this in labs and test servers.
"Uninstalling and upgrading from this prerelease is not supported. Citrix recommends that you rebuild your server before installing the final release and/or before upgrading to the next version of XenApp. This prerelease will not be supported once the official version is released."
The HRP2 beta was released quite fast after the last hotfix they included. Citrix should get more feedback on hotfixes before packaging them into rollup packs, even if they are unofficial.
The official HRP2 hasn't been released yet... Stay tuned.
Should Hotfix Rollup pack 2 be released, it is advised to wait as well to deploy this in production. Citrix often released urgent Post RP hotfixes, after some problems that occured at customers.
I advise to wait at least 2 months before implementing a RP in your environment, and so you can install the first post-HRP hotfixes too.
Hotfix Rollup Pak Release schedules:
List of XenApp 6.5 official Hotfixes and Rollup Packs: