I too was disappointed with Prometheus. Tried to cover a ton of base plot line and failed. *Spoiler Alert* With that ending though, there will probably be a second one. Hopefully more action this time.
To add my own: I would have to say Speed Racer or Green Lantern. Both boasted epic graphics but Speed Racer was a drama more than an action and hard to follow. I felt ashamed after watching Green Lantern because I didn't have a 5 yr old with me to justify my presence in the theatre.