5 stars! The system actually can cover a multitude of genre and settings, and retains an element of chance without dice, via the different levels of Effort used. The rules are unified well, no matter the actions, and this doesn't feel forced!
And then there are the setting and genre books for it. I'm quite fond of some of them, and since they have to devote little space to system - the text is already a system - they're quite packed with information!
(As an advice, though, the GM should probably scribble the difficulty of the task down after determining it, and reveal it after the player has decided the Effort used. It only takes a sheet of paper that you can also use to scribble notes on).
Besides, it's free! Try it, you've got nothing to lose even if you don't like it - but if you do, you have found a very sleek, very adaptive system that's to your liking!
[5 of 5 Stars!]