I find it is almost too deadly in the hands of a master. Luckily it is quite limited by range, otherwise I'd clear whole maps with just a couple of master psi users, never firing a single shot of any other weapon.
I guess that goes for most psi stuff in this modpack actually, it is extremely effective once you get into range and have a decent psi user, but you can't just win the battle from inside the skyranger. Which is good, and forces us to use more complex strategies.
I don't know if all the details of how this works is easy to understand though, with how range, strength, skill and energy all play together.