I would have to disagree with the above writeup from Jet-Poop. The system hasn't become more complicated, it's that all the complications from previous editions has now been baked into the base book.

The new edition of GURPS is written so that all of the rules are in the main rulebook now. It's filled with enough options that you can literally run any sort of role playing game with no need to buy any other books.

Since they're trying to mix Superheros with gritty fantasy and with space opera science fiction, it means that you get this mishmash and everything is sorted together alphabetically. It would have almost worked better if the rules were presented with a nice piece of computer software which could filter out what you don't need.

It's the GM's responsibility to model his setting the way he wants. So, he'll end up having to act as that piece of computer software. He'll go through and filter out things he doesn't like, telling the players "Ok, these are the things I expect you to find useful in my game." Steve Jackson Games does provide a tool which lets you filter the various things, but I'm finding it easier to use the character generator that they're selling to do it. Once you've done that, you can allow your players to use the character generator and make it much easier for them.

Superhero rules are the main source of complexity, if you ignore them you've probably cut 1/3 of the book out. Now, granted, what makes a given setting interesting is where it diverges from what you expect. So, it's handy to have the super hero rules around, so you can model up one of those outlier abilities that some heroes might have. Though, if you're finding the rules overwhelming, it might just be easier to cut out all of the exotic and the supernatural abilities, and do a simple game. You could do a pretty interesting mystery with just a normal realistic setting, or even do a horror campaign where the villains have one or two of those abilities you're trying out until you become more comfortable with them.

You can see how all the rules are in the main book when you actually do purchase the extra books written so far. I've picked up both Space and Fantasy, and there's almost no rules in that book. For the most part, they just tell you how best to apply the tweaks that are written in the main book so that you can end up with the setting that you want. They are in the business of selling books to make money, so they're going to keep making new books. But, this is the one campaign that I feel comfortable that the new books aren't going to somehow change things I had gotten used to. (Which was always a problem I had with the d20 system over time.)