Really glad I saw this on the big screen as the cinematography is amazing. This movie was clearly shot by seasoned rock-climbers. If you have a single drop of vertigo in your body, you will feel it in this one. Also glad I knew nothing about this free solo rock climber beforehand and I'd strongly recommend not reading up on it before seeing the film.
One sound bite that you hear one-third into the film that haunts you for pretty much the rest of it was, "none of the well-known free solo climbers are alive." So this one scene of the day before Alex attempts to solo climb El Cap in Yosemite, when he's talking to his g/f and you realize he's trying not to tell her that he's planning to do it, but she senses it.... it's actually one of the more stressful scenes in the film. You feel her concern, you feel him wanting to protect her from this and keep her out of it. In fact, that whole relationship is a really cool part of this documentary. When they buy a house together and she's measuring everything and he couldn't care less.... these scenes will speak to a number of us in different ways.
At one point I was wondering how immersed I was in the movie (always a sign that it's a good one), after Alex had got up at 3:30am in order to attempt a free solo climb. I'm looking at the movie and I'm wondering, "He didn't want to tell his g/f he was going to try it, I wonder if he told the film crew..." and then ultimately realizing I'm watching footage of him walking as I'm actually thinking this. So obviously SOMEONE is filming this. At that point I realized I was fairly immersed in the movie :)
It's an astonishing movie and most of the real drama is watching his filmmaking friends' reactions to Alex doing free solo as they wonder if they're about to lose this friend of theirs. Some of the filmmakers can't even watch and they're supposed to be making a movie! Those scenes are gripping and remarkably dramatic.
The other part that really spoke to me was at one point Alex says that casual rock-climbers will think it's cool and will 'get it' as to what Alex is attempting by doing free solo climbers. Whereas any true professional hard-core climber will think he's absolutely nuts. Slipping and losing footing is a very normal part of rock climbing. I did it in college and it was nerve-wracking to say the least.
Imagine doing it without gear.
Imagine trying to do it up a 3,000 foot slab of granite.
...can't imagine it? Go see this movie.