it's a nice pet, but compared to things like the corallax or the fortunata, it somewhat pales.
at least that was my experience pre-i13 on my fire/cold/mace.
I've done all the patron powers and the corallax and fortunata are nice for the damage type, but the disruptor is my favourite by far for corruptors. The disruptor has a shorter recharge on it's immob. it's immob has a larger radius. The psi shockwave is nice on the psionic's when it happens, but it's not used that often and usually doesn't have a significant effect. The bot also has very decent resists. So decent that I made one of the four slots in him the expedient reinforcements +res IO and now he can solo tank large spawns by himself while keeping many of them locked down in immobs.
Just wanted to get some input on Summon Disruptor. I know basiclly nothing about the power. Any thoughts? Is it worth taking for the purpose of getting more damage?