I like having another option to end a god run besides obliterating now. He feels like a much better late game boss than Mithrix, who can just delete you in phase 3 after he steals enough items. When too many Void Jailers spawn, you are spending half your time in the void field zone dodging the instakill void explosion zones which is super annoying. I think my only complaint isn't about the Voidling stage or boss fight at all, but the Void Lotus stage where you charge the signals before going into the Voidling stage. Voidling still scales super hard health wise like Mithrix does and is a real threat, but is possible to beat even after you have had your fill of a god run.
Mithrix had the problem where if you fought him after stage 10, he would steal so many items that there was basically no way to beat him. I do like how they made a final boss that you can kill after a god run. To unlock him this way, you need Void Fiend vs Voidling (NEW DLC BOSS) Risk of Rain 2 Web03.
I've fought him 3 times and beaten him all 3 times (although my friends I was playing with have died all 3 times, so not sure if my build was super good or if my friends are bad at dodging). two ways you can actually unlock the Void Fiend.