All in all, I am happy I made the switch. SDL is simply a more robust library, in my opinion. That being said, I do miss some components of Allegro, such as Allegro's text output functions.
Oh, and in the title I seem to have mentioned Half-Life 2. Yep, I just bought Half-Life 2 a few days ago. Now I know what you are thinking, "Didn't Half-Life 2 come out in like, November?" Yes it did, but I just decided to get. I love the game, although the graphical glory sometimes cripples my video card, and the framerate drops.