I didn't care much, cause I didn't have to use it, but... reviewing it, it didn't make sense. People using it were having to take a lot of time to do basic stuff, and ... people were constantly waiting for the main guy to 'finish up' the next bit that would save everyone 'lots of effort'.
Some of the other 'sr' people there fawned over it - "he's a genius! this code and system is amazing. it's so hard to understand the brilliance, but that's because he's such a genius" (near exact quotes from his internal fans).
Again - wasn't on that team, didn't care. Then... I was told to use it. For a project that needed things well beyond what it had in place. We needed session mgt, authentication, caching, solid XML support, etc - everything this 'framework' didn't have. I criticized it, saying we shouldn't use it for this new project.
What complicated this is that I'd put together a framework before I'd started working there (with a team of other folks). It was far more feature complete (not great but functional). I was accused of being jealous, and wanting to use my system, etc. Well, yeah, I'd like to use my stuff, cause it checked the boxes we needed, and I'd used it for several years, and could be productive in it. But... I said "take my code off the table - it's not about me. System X is just not usable for our project needs - we need to plan to build something new, or spend time building out all the missing stuff."
What a shitstorm that became. Internal fighting between people who'd never looked at the code, but insisting it was fine, and that I didn't understand 'enterprise' work. I left - turned in my two week notice (not 100% over this, but it was a factor). The day after I left... the "genius" quit the company, without telling anyone, no notice, just... left a voicemail saying he quit.
I remember that one of them even mentioned that the asshole was so brilliant that he wrote code sometimes even the asshole couldn't read.... the manager didn't seem to twig even after writing that that this was a glaring klaxon warning signal that he was an extremely mediocre coder.
IME the most toxic behavior in this profession derives from insecurity, not intelligence, and most of those "brilliant assholes" were actually assholes because they were hoping that their mediocrity wouldn't be uncovered.