If you are talking about the AARP paywall here is a summary of what I see there:
Most of the trash talk I have seen on the forums is medigap rate increases where it is clear people don't understand/remember that there are declining discounts through a certain age and between "normal" increases and their declining discount each year what they personally will pay will climb faster while there are still declining discounts than it will after they have run out of declining discounts. They don't understand community rated risk pools and what that means for when they are older with respect to rates that eventually will be cheaper than age attained or age signed up rates for someone of the same age/signed up at the same age with another company. I don't really see anyone complaining about the actual medigap plans themselves.
The second frustration I see is with, as you state, MAP plans - usually around denials, delays, the problems getting denials overturned in a timely manner... generally those threads are focused on a particular, personal/family member horror story. That, of course is not unique to UHC.
The third frustration I see a lot of is with some of the customer service people, some of whom appear to not be all that well informed and callers don't realize that they can't answer some of the questions, only the agents can but then don't refer them. That, of course is not unique to AARP UHC either.
The article I posted about the billion or so that AARP gets for "royalties for use of it's name" is not behind a paywall. At least it wasn't when I clicked on it initially.
I'm referring to the OP.