It's that they've made the PC version literally the exact same as the console version. In doing so they've removed dedicated servers and custom mods and replaced it with a peer-to-peer matchmaking only system. This removes any ability for custom content (be it maps, mods, ect), large games (9 vs 9 now in MW2), leaning has been removed, no command console, and charges PC goers $10 more than normal PC games.

Compare that to the first one where you had dedicated servers (lower pings, clan, and community support), custom content (server mods, game mods, maps, ect), 16 vs 16 players (officially, but you can also play in 20 vs 20 servers), leaning, console commands and more tweakable settings, and it launched at the normal PC game price of $50.

Essentially the things that would come to be expected in a PC version has been changed or removed in Modern Warfare 2 and they're charging more for it.

But hey, we're getting the ability to actually tweak our graphical settings so we should be grateful! They've also made sure that everything has been balanced for lean

I see. That's.....a lot though, I can see what the gripe is about. Especially since PC gamers have been used to the whole hog over the years. At least it got better graphics...............................right?