We saw Terminator: Salvation on Sunday, and I liked it. That isn't to say it was a great movie, but neither did I expect it to be. Unlike Star Trek, I had no idea what it was about, save that Christian "Psycho" Bale was playing John Connor.
I think this is a pattern for me. I loved Iron Man last year, but hated the Dark Knight. I am by no means an Iron Man expert, and was willing to forgive minor alterations to the Iron Man mythos. But you put Batman, the Spirit, or Star Trek into a new form, and I get relentless in my attention to every last detail. On the other hand, I loved Watchmen and I have a really strong familiarity with the material. I guess it's just hit or miss, but it sure is easier to like something when you go in not caring whether or not it's any good.