Things that piss me off:

They never confirmed a trading system, but made people think they did.
The only teammates I actually CARED to meet were the medic and the pyro.
Left4Dead was terrible.
Left4Dead2 will be terrible.
Episode 3 would have sold better and been better than four sequential of Left4Deads put together.

things that amuse me about valve:

They have a sense of humor.
They like to troll their fanbase.
Gabe newell is morbidly obese.
They are letting Cryengine win.