The game is not available for PC.
Yes, many still enjoy multiplayer on PC versions of older Call of Duty titles like Code 4 and Mw2.
Yes, some games are available on consoles.
The question is what you're asking.
MW2 remains widely used despite changes.
Original and modified server version
I can still locate games on MW2 easily. Of course, I only play TDM.
Absolutely, I used to play on the Xbox 360—it was quite lively.