To MAGAs she's terrible and nothing will change that
To progressives she has massive policy differences, but at least she is aligned with us on basic democracy - something that should be a basic thing but isn't. What's she going to do, get progressives to vote for Trump?
To people who still cling to the thought of "your father's Republican party" - those who hoped Nikki Haley could somehow get Trump off the ticket early because they know he's an idiot/traitor - they could use that person to convey the message that yes, this is a Democrat but yes, you can and should vote for her because Trump is fucking bonkers and in no way represents the party you are clinging to in your head right now.
If people like Liz Cheney can get people to vote for Kamala Harris over Donald Trump, I'm all for it.
I suspect Cheney is a toxic brand though. Over at the new blueprint polls, people for some reason trust Trump over Kamala in the category of election integrity. Adding Cheney to the crew might hurt as much as it helps.
IMO, those who know who Liz Cheney enough to think her brand is toxic know her well enough to know what's happened in the last 4 years and why that would put her in that position. And that "why" is much more important than "who"
There are more people that don't know Liz Cheney but will recognize her last name than those who understand what was done to her. Those people are primed for Trump's argument that Kamala represents a corrupt establishment.