In my first playthrough, I played a mad bard and ate all brainworms, and breezed through act 3 spawning an endless army of displacer beasts. I have mostly ignored the illithid powers since then. I do find the lack of consequences beyond minor dialogue tweaks and the need for thicker makeup disappointing.
I feel that illithid powers and the Slayer would've been better with abilities that line up more closely with the abilities of the classes, give it exclusive abilities based on how many levels your character had in class. Let's say 5 levels in rogue would give you an illithid power that causes enemies to turn and look away from your current location or 11 levels in druid would surround the slayer in a poison version of Spike Growth that gave enemies disadvantage on their saving throw against it.
Regarding how it is presented in the story? I think choices kind of hurt it, and contradict themselves. The tadpole is a cou tdown to a death that erases you in body, mind, amd soul so you better cure it quick! But wait, that Omeluum is a pretty chill squiddie, amd seems to have quote the budding friendship with Blurg? Karlach is happpy she turned into a walking hentai?? You can just eat ethically??? I think those are good for giving you a lot of choices for an individualized story but on a meta level I think it makes things a bit messy. The natural counterargument is that it should be read as an individualized story and not viewed at a meta level...but I want to XD
I do think there's an extra layer to the Emperor claiming to be "just like you" as well. He does whatever he needs to in order to destroy the Netherbrain and return to his old status quo, just like you when you used your squidward powersto bully Absolutists when it suited your needs. The Emperor encouraging you to transform clearly isn't altruistic, it's just what appears to him to be the most effective means of reaching a currently shared goal of defeating the Netherbrain. I think it's very telling that the Emperor gives you unique dreams in coop, and that siding with him gives you the option of parting ways quite. At no point is the Emperor evil, he just wants to survive...just like you, maybe? The game wants us to be empathetic towards illithids that actively fight their nature, and we can see that in how video game-y that most stickiest of kitties, Us is presented.
Sorry if that seems rambly or muddled but tl;dr is I'd like more significant consequences and everything about how the game presents illithids is a bit inconsistent.
Patch 7 brought something extra for the uninhibited tp consumer. Warning : endgame spoiler. If you're close to the endgame, perhaps it's better to wait to read this until you're done.
If you didn't transform for the final battle, then after victory decide to dominate the netherbrain and become absolute, you can't stop ceromorphosis. So your plan to become ruler of the world in your current incarnation turns out to be a disappointing failure as you transform against your will.
