What is Reddit's opinion of Gravitation?
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By popularity on Reddit, this product is:

#21 in Astrophysics & Space Science books

10 reviews of this product found across Reddit:

>Personally I've been very happy with this one, but I'm not terribly familiar with the comparable books you could choose instead.

The one my intro GR course used was the intro to GR book by Schutz. I liked it, but from what my instructor told us it is much less rigorous than the one you linked.

John Wheeler trivia: the textbook he and Misner and Thorne put together is both the largest text book (also known as the phone book) and the most readable book with thousands of tensors in it I have ever seen. Seeing it is out of print is nearly as strange as it would be to see Feynman's lectures out of print.

Kip Thorne (the T in MTW) was a science consultant for the film. They got it pretty right dude. Yeah the whole [spoiler](#spoiler, "Inside the black hole") part isn't scientific, but it was adequately explained and motivated. If you can't handle something like that science fiction, as a genre, is not for you. Everything else was based on real physics and far more accurate than we could ever have hoped for. They ignored the gravitational red shift so that we could see anything... because it's a movie. That's fairly reasonable. And [spoiler](#spoiler, "The ship left in orbit when they went down to the wave planet should have experienced just about the same time dilation as the people on the surface"). But that seems like a minor nitpick.

Thorne (+Misner and Wheeler's) Gravitation is by far my favorite.

Highest price I've seen is around $800 for a new copy of Gravitation by MTW (known as "the bible of GR").

edit: 800 CAD I mean. 600 USD.

Well, for GR, I recommend Misner, Thorne, & Wheeler.

I can't personally recommend a good graduate level QM or Thermodynamics textbook, though if you're weak in thermo, you might want to work through Kittel and Kroemer, which is what I used for undergrad thermo/stat mech.

It's also worth noting that "QM and GR" is a very broad area of interest. You should consider looking at some special topics in each to consider what specifically you might be interested in. Since you liked coding, I suggest looking into different applications of numerical relativity.

Added sources to my comment. I should have stuck them in originally, but got kind of carried away with just writing it the way I thought of it. Kip Thorne is one of the authors of Gravitation and advised on Interstellar resulting in this fucking awesome scene.
I don't know what qualifies as "proven theory" but I don't think anything I have said is regarded as controversial within mainstream physics.