Their model is based on advertising revenue????
So how many ads have you seen on your mobile facebook app? I have seen exactly none.
If the world is moving to mobile devices then their model, along with many other sites do not work.
So would I invest in them. Hell no. They would need to rectify this ASAP or they will be going the way of the DODO!!!
Facebook = Deadbook unless they move their ass. Same fate awaits many...