Ever watch 2001: A Space Odyssey? I love it, but man it's slow.
Also it's a movie that asks more questions than it answers, which annoys a lot of people.
I saw Terminator 3 in the theater. The first 20-30:minutes, with that crazy chase, I was like, is this going to be the whole film? Eventually it does show down and take a breath, but I still remember my initial reaction to that.