I tried this once at work, because it seems like such a trivial task. Spoiler: it wasn’t.
Having said that, I learned a lot from it. So I wouldn’t say don’t do it. You’ll probably learn from it. Just don’t expect to make the next MongoDB or MySQL :)
I can't find it right now, but there was a collection of crazy stuff he said on IRC while Quake was in development. Basically promising the world (e.g. the dragon). Very energetic, but clearly not well thought out.
I loved the part where he was still with id; how he grew up, and how id came to be. The magic of that founding id games makes you wish you were a part of that group. After that, the Ion Storm stuff gives some context to the failure, which was interesting to read. But it becomes a bit more incoherent. Towards the end, post Ion Storm, it just feels like he's going through notes he wrote down, and you're reading them in a chronological order. All in all one of my favorite books, but the end was a bit of a drag.