@talkbitcoin thanks for the question
We don't offer a free trial, but you can pay for as little as an hour of usage.
For trust reasons we didn't want to go down the route of supplying a custom connection client, so there isn't anything to install. Instead we rely on functionality that is built into most *nix based operating systems. Admittedly that means Windows support is limited... so we're really pitching at Linux/OS X crowd.
See here for more details
https://szilla.io/guides)
In terms of the protocol, we actually use SSH, which has a few big benefits. The main advantage is an inherent level of packet anonymity, which means your ISP won't know that you are using a VPN (as with Open VPN). In turn this is great news if you are in the UAE, China or similar.
Overall I'd say that our aim is to be as transparent as possible. By engaging with the community we hope that we can improve, while gaining trust.
The Szilla Team