This game has been generally regarded pretty highly, in particular as a low-prep pickup game, so I finally decided I should get a copy. Getting it out of the package was a little intimidating - it's a big book for a pickup game!
Getting into it, it becomes clear that the size of the rules is not going to detract from the ease of play. The core conflict mechanics are very simple. There's a number of special systems for certain situations (groups of mooks, car or plane chases, etc) but these are nicely self-contained and not inordinately complicated.
Character generation is absolutely inspired. You basically build up a character by answering some questions about each stage of their life and then picking aspects (more on these later) that go along with that. Then you get to the bit that makes it - you name novel your character first appeared in and write the back cover blurb. Then pick some aspects. Then you get to guest star in two other novels (and likewise, you get some people appearing in yours), adding a bit about your character to the blurb and gaining another aspect. Very cool stuff! (Aside: this one guy posted on Story Games about his group going one further... look and be awed)
So your character gets defined by skills, aspects and stunts. Skills are your basic things that anyone can learn. Stunts are the super pulp abilities you have, and there's a nice big list of them that looks to cover almost anything you might want (the stunts list is just under 100 pages long).
Aspects are player defined phrases that work as an advantage or a disadvantage in play. Basically, you can spend a Fate point (basic 'I do cool stuff' currency of the game) to get a bonus from an aspect. The cool new thing here is compelling an aspect. This normally occurs when the GM does it - basically saying 'your aspect X means you now do Y'. You then get to decide whether you do Y or not. If you do, you gain a Fate point. If you don't, you have to spend one. This seems like it's going to be pretty cool in play, given the big temptation to do the thing that will complicate your character's life in order to get the points. Nifty.
Then the book goes on to the advice section. A whopping 100+ pages of advice on how to run the game, how to run it without preparation, pulp story structure to use, some rules stuff and setting details and a sample adventure.
That advice on running the game is some of the best and most thorough that I've come across. It's packed deep with cool ideas, how to cope with this or that situation in play, how to remain focused on the characters and plenty of other stuff that you'll need in the game. Although it's focused on the pulp action that Spirit of the Century is all about, a lot of it is more widely applicable.
Overall, very cool stuff. I look forward to playing it.