Sherlock Holmes was fucking awful, so if you are comparing Shutter Island to that then I just became very disapointed.
Sherlock Holmes was a great film.
Anyways my take:
Shutter Island was ok. It wasn't great. But it was ok.
Good:
The ambiance created was incredible though. Every visual detail was worked perfectly and it all comes together in such a way that it completely absorbs you into the film. Considering the director, it's no surprise though. Scorsese is a monster.
Maybe I'm just warming up to DiCaprio but he did a very good job. He's no Anthony Hopkins but he plays his role very well. I think I've read before that he's a method actor and it really shows in the film. He gives off a very convincing portrayal and was probably one of the better choices when casting was being considered.
Pacing of the film was very good. And the flashback scenes weren't detrimental to the story either. I hate when you're confused as to what's going on in these psychological thrillers because they sometimes introduce flashbacks and you start to wonder if what you're seeing is "a mind trick" a "true flashback" or a crappy "plot device." This wasn't the case in the movie. It has a pretty fast tempo and the plot never dragged.
Bad:
Cliched story line. It's been done. And it's pretty predictable.
Leo's accent. It's just horrible.
Conclusion:
If it wasn't for the ending I might have liked the film more. Its been done far too much and it really isn't a twist as much as a 'get out of jail free' card that script writers use when they're stuck for ideas. Although, I guess you can't really fault the script writers for it since the movie was adapted from a book and the film is supposed to be very loyal to the source material. I guess either I just didn't like the ending or maybe it just doesn't transition to film very well.
Regardless, I would go watch it. But probably during matinee hours. Just my two cents.