I'd say it is. There are some really interesting pictures, like a bunch of monsters that got cut from the game, as well as some early models of characters. Also, there are a few design documents and short stories scattered throughout. These show off some stuff that got cut from the game before release, like an Air Exchange plant (which replaced Earth's air with noxious Combine gas) and an Arctic weather station. Plus lots of other weird information. For example, that an early suggestion for Gordon's name was Dr. Dyson Poincaré. And that Alyx's original father was a military man named Captain Vance, who, like Barney, worked for the Combine but was secretly allied with the rebels. If that sort of stuff interests you, by all means get it.
Hmm, my mom used to work in that building, on the floor below the top floor. And I too can attest to its major design flaws (right down to glass elevators. It's not enough that they're small boxes and that half of them don't go up all the way to the top, but they're designed to be hot as well?) Also my kindergarten was for a time in the Old State of Illinois building next door. The playground was on the roof, so you had to be careful not to fall to your doom. Ahh, the joys of big city life... Anyways, back to Romero. Neither he nor Carmack impresses me very much as game designers, because neither of them seems to be able to write good stories for games (one of my major buying criteria). I guess that's why I got more excited over the new Half-Life game than over DOOM 3.