Stranger in a Strange Land is really like two novels. The first part is good, classical Heinlein. The second part is some kind of rambling political pamphlet that always manages to bore me. I read somewhere that they were written with several years difference, and it shows.
I hope they base it in the first part, really. Well, probably, if it's a typical TV product, they will take the basic idea and massacre all else, so why do I care?
"Rambling political pamphlet" pretty much describes most of the Heinlein production
I think you consider the first part of Stranger in a Strange Land as "good Heinlein" just because you happen to be familiar with the ideas presented.