I find that a lot of the time, trailers are nothing like the game when you play it and that can leave you feeling disappointed as a gamer, especially if you had high hopes for the game releasing.
I would love to see game trailers be more true to what the game will be like when we play rather than making it look like something it is not, obviously don't use a lot of what we will see in the game as that will spoil things but I feel we should see something that we expect to see when we finally get to play.