
The best thing about OpenVPN AS is that it is pretty much literally a turn-key product. They have a virtual appliance available that works out of the box with NO installation, per se, required. Review collected by and hosted on G2.com.
The downside of AS, however is that a lot of the detailed configuration and control options are only available via a command-line interface, which is not exactly intuitive. It is, however, quite well documented and there are numerous forums online where you can find how-to-do whatever it is you are needing to do. Review collected by and hosted on G2.com.