When I was gearing up to buy a beer kit, I was all for glass. I thought, what could be better? And, certainly, someone of my pedigree would never be caught brewing in plastic!
But a thread similar to this had a link to some serious, serious, serious horror stories from glass. One guy had a glass carboy literally implode in his hands while he was rinsing it out with water. He ended up with some mangled hands and mounting surgery bills.
Many more stories on there of dudes just dropping them accidentally. Keep in mind, carboys are under pressure...not a ridiculous amount of pressure, but pressure nonetheless. The guy above talking about chards flying is not far off the mark.
After reading all that, I said F*** it and got Ale Pales (buckets, basically). In my opinion, buckets are the best: they don't let it light, they have a nice, big opening for dry hopping, stirring, etc...and they're cheap!