I prefer glass pans in almost every instance. The only real cons with glass is that they are heavier, which is kind of annoying when you are loading and unloading a lot of stuff from your dishwasher. The other issue I've had on rare occasion is that the glass dish will sometimes shatter when taking stuff out of the oven. I think this is more of a problem with certain versions of Corningware though from what I've been reading. it's only happened to me twice and thankfully nobody was hurt.
Glass can hold up to rough cleaning much better than metal pans, especially when something is really baked on. Metal pans start to rust and chip, particularly if they have non-stick coating. Glass is also better if you are making stuff like a baked pasta dish, and you don't want to worry about the metals in the pan reacting to the acid in the tomatoes. I also like to be able to see how the food is coming along while it is baking - it's a little easier to tell if something is done or not since you can see the sides of it.