I like the boss fight as a boss fight. Honestly I think it's the best boss fight in the game so far.
I have a few things that have really ticked me off though -
Thermia Canisters in Phase 1 need to be marked - I wasted two solo runs before I eventually found them
The orb should NOT be able to climb onto the mountain - this makes it way too difficult to kill all the coolant raknoids, especially the ones that spawn on the other side of that ridge
I think the general difficulty of the boss a tad high to do it solo - Mostly the increasing level of the coolant raknoids along with their numbers and point 2
The whole 'Shoot the Canister' thing is weird, especially in the second part - Just have us throw it at it.