(It begins...)
Honestly, I would probably rather not have the crossover.
I will only be able to play it on PS3, and I do not want to have to go up against some dude with a mouse. He's gonna headshot me every time.
Not just that, I think Valve sucks at making console FPS's. Both of the Left 4 Dead games had atrocious controls (the concept of the games was so good the controls didn't much matter). It was obvious that Valve did not do much in terms of fine tuning the controls for console to make them control as well as most other modern console FPS's. I'm hoping they improve their track record. Portal 2 on console was better than Valve's previous console attempts, but it's hard to compare that game to a tactical shooter where split seconds and millimeters are often the difference between relatively equally skilled players.
This Cross-Play is only a feature for PC players. As someone who'll be playing it on the PS3... me no likey.