To be very clear, and up front, we've only spent a few short hours with the game, but so far we are VERY impressed.
The one thing that we were a little disappointed with was the fact that Call of Duty 4: Modern Warfare doesn't include a "cover" feature like Gears of War. We love that game feature so much; we wish everyone would adopt it.
We quickly forgot about this as we ran through the quick tutorial, and initial single player levels of the game. The controls are slick, and the game is simply beautiful. The soundtrack is great as well. You can practically feel the tension dripping from your TV screen and sound system.
Having tasted the single player, we had to hook up to Xbox Live, and see how well the multiplayer was done.
We weren't disappointed. They definitely spent some time with the multiplayer, allowing you to play as different classes, weapons, etc. The voice communication is a must-have for this game. The minimap helps a ton, and the red dots showing where other units can see enemies is great, but being able to plan and coordinate via voice adds a whole new level of tactics AND realism to the game.
Right now, Call of Duty 4 looks like it may be giving our favorite first-person shooters (Gears of War and Halo 3) a run for their money.
Look for our official review in the next few weeks.