I wouldn't say I *hate* Panam, she has some of the best lines in game, and her can-do attitude is fantastic, but I think she gets a free pass on a lot of flaws, as criticism is often met with 'dAt ASs tHo'
I think my dislike of her mainly stems from her tantrums. I generally don't mind characters with anger as part of their personality - I like Judy and Kerry a lot in fact - but Panam's outbursts feels like she's doing it because it will get her her own way, rather than anything else. In the first mission with her, V is literally there to help solve her problem, and she just doesn't want to listen. Then after V does hash out a deal were everyone gets what they want, Panam tries to change the deal to get revenge after V fills their side, and Panam has yet to fulfill hers. If V refuses, she blows up, and even throws in a gaslighty 'I thought you were more than just a for-the-pay-merc' comment, which is odd, considering at that point she and V have known each other than less than 24 hours, and depending on V's dialogue choices, she could have been fantastically rude to them throughout the mission.
Her interactions with Saul as well don't paint her in a great light. In particular, when she and Saul are trying to settle their differences during the storm, he makes a completely fair comment that she can't expect to be first in line all the time, that she's one of the family. Again, she becomes scathingly angry, like she expected her opinion to be front and center upon her return. That sort of carries over to the next mission, were she informs V that the veteran Aldecados agree with her plan over Saul's - but looking around, there are dozens of Nomads not involved with her plan, and her group numbers about 5-6. It implies that Panam wasn't sure the vast majority would go with attacking the convoy, but she does it anyway, knowing it will affect all of them, regardless. This isn't to say Saul is right, but the fact she dismisses a huge portion of her family is, as the kids would say, a yikes from me.
Also, Panam never paid me for doing that convoy mission. This was a glitch. This is not Panam's fault. I am still salty. Anyway.
Also also, having to repeatedly tell her to back off with Vincent got a bit tiring after a while. River still takes the Creeper Crown, but honestly Panam's inability to take 'no' for an answer got a bit uncomfortable as the narrative went on. I know this is 100% the writing, as Panam comes across as the 'default' LI - another poster said she was like Liara, and it is exactly like that; it's like the game cannot conceive the idea of a V who just ain't into her.