Would somebody mind giving a quick explanation of how aspects work?
Basically, when you create your character you write down a whole bunch of "aspects." Aspects can be adjectives describing your character (bookworm, gadgeteer, stubborn), magic items that your character owns (magical sword, one ring of power) or important elements in your character's background (long-lost parents, grew up in thieves' guild.)
You also start out with a reserve of "fate points" which can be used to "tag" an aspect. Tagging an aspect costs a fate point and gives you a +2 bonus to a roll related to that aspect. (That's a pretty sizable bonus, given that rolls are skill + (4d3-8)). For example you could tag "gadgeteer" to get a bonus on fixing a car, "magic sword" to get a bonus to your attack roll when wielding the sword, or "grew up in thieves' guild" to get a bonus to know where to find a black market vendor.
Also the DM can "compel" an aspect by paying the player a fate point to force him to act in accordance with the aspect. For example, the DM could compel a "stubborn" aspect to force the player to stand firm in a negotiation even when compromise would help them achieve their goals easier. The player can "defy" this compulsion by refusing the fate point and instead paying the GM one. Also the DM can give the player a fate point to introduce a complication based on the player's aspect (e.g. compel a "gadgeteer" aspect to say that the character's invention goes haywire and threatens the town.)
While this has potential for a lot of unrealistic or illogical scenarios (why does my magic sword stop working just because I picked a whole bunch of locks a while back (spending all my fate points to do so)?) it also has several advantages:
1. It's simple and universal. Almost any character trait you can come up with can go into the same system, with no additional "rules engineering."
2. It's self-balancing. If a player tries to "twink out" a character by choosing only aspects that are as broadly useful as possible (outstanding luck, offspring of the gods) and using them as often as possible, all that will happen is that he runs out of fate points earlier.
3. It eliminates or at least drastically reduces the "guessing game" aspect. There's no need to worry about "wasting points" on an aspect that you won't use because if you don't use it it doesn't cost you anything. And you can't try to take a flaw that will never come up in order to get "free points," because you only get points for a flaw when it comes up in play.
4. It encourages creativity and in-depth characters. Since the main way of getting fate points is to have your aspects compelled, you have an incentive to come up with interesting aspects that will provide more ideas for the DM, so that the DM has opportunities to compel your aspects. In particular, one thing it encourages is multifaceted aspects - aspects that can be good or bad depending on the situation (for instance, "bookworm" could be useful in order to research how to counter an alien threat, but could be a liability if the character has his nose buried in a book so he doesn't see the alien creep up on him from behind...)