Don't really know how people make these decisions without reviews.
I never pre order games. I honestly think MW3 and BF3 will both be let-downs. Don't see the point in over-hyping future FPS games on PC.
Because reviews are not your own opinion. I've played many a game with a 4/10 and loved it, and many with a 10/10 and thought it was complete trash.
Reviews are useful if they highlight possible good or bad points you already expected, which can confirm your choice but i've never ordered a single thing in my life purely based on a review.
Also, pre-ordering is very worthwhile on Amazon for instance. I pre-order games i may not even buy because you often get them cheaper!
I got Dead Island for £32. even though it was £38 on release day and is actually even more expensive now!
I voted BF3.
I'm getting it for 360 because about 5 or 6 friends are.
If my friends did not play it, I would not play it. I don't dislike FPS games, but at the same timee i have no interest in multiplayer with random people so i don't play them by myself.
Due to there being a good group of us, BF3 is by far the best choice due to it's emphasis on teamwork.
MW3 really doesn't seem to offer anything worthwhile, and the last COD i played properly was MW1. But if i fancied an FPS, and did not have a group of friends to play with i'd probably go for MW3 because it's easy to control a game with 1 player, and impossible to on BF3.