I'm guessing you missed it in the theater? That's a movie that works really well on a big screen but at home it can be hard to get into. Especially if you missed out on the theater experience the first time 'round and so have no residual memory of that experience to push you through. I bought the Blu Ray but I'm not really sure why because I haven't watched it since I bought it but I also agree with Hoovtrain that it was one of the best movie watching experiences I've had in a theater. It basically felt like I was falling and gasping for breath for 90 minutes straight!
I guess if you do want to give it another go, you could try to recreate the theater experience as much as possible. Find somebody with a big screen and a loud sound system, watch it with a group, make yourself a big bowl of popcorn, turn of your phones so nobody will be distracted, and commit to sticking it out all the way through. You'd still be missing out on the 3D but it's more of a thrill ride than a traditional narrative so I think you have to give yourself over to it to a certain extent to really get what the appeal is. Then again, if you've already tried 3 times it might be best just to give it a pass.