I'm developing a game and the sfml website is down:( it better not be down long the url is www.sfml-dev.org .....someone check and make sure my computer isn't being stupid plz
All you SFML people... I'll stay with Allegro, somehow I feel it's easier to use (not that using SFML would be hard, but Allegro feels more natural to me).
SFML is better because it's modular, so you can use each part of it separately. For example, if you only want to do audio, you just link sfml-audio, if you only want to use the networking module you only link sfml-network. You can also combine them however you want, so if you were streaming audio across the network you would link sfml-audio and sfml-network. If you only want to use SFML for cross-platform OpenGL use, you only have to link sfml-window. If you only want it for 2D graphics you link sfml-graphics and sfml-window. (note: you always have to link sfml-system).
It's also better in that no matter which modules you link, it always behaves as if they are a single library. What I mean is, with SDL, you have extensions like SDL_Image, SDL_Mixer, etc., but they all act like different libraries. Instead of SDL_LoadBMP, you have IMG_Load. It sounds superficial, but it shouldn't be like that. When you link an extension to a library it should behave as if it were part of the core library. It should tie in. Otherwise it feels like you're using too many different libraries. SDL actually ties better with OpenGL than it does with its extensions.
SFML is also more modern (it transparently uses hardware rendering when it's available, which SDL doesn't do) and more complete and it has C bindings so you can use it in C code (which I've yet to try).
I do like SDL, and I do use it in C, but SFML is superior. I have to say, though, it is far from perfect, and a lot of the changes in version 2.0 are superficial and annoying. Also, there are a lot of things it can't do that it really should be able to do, like changing the window title after the window is created without creating the window again (IIRC it works, but it's a dirty hack).