The plot was actually interesting. Well I agree that the story was rather predictable, but I still enjoyed the movie a lot. The only complaint I have is, the movie editing could have done better. The transition between scenes weren't that smooth. But that didn't affect the movie plot, more to technical stuff. The lead actors and actresses' acting were all really good too.
Overall, Somewhere Only We Know was a good movie. Since it was a pure romance movie with a very little of comedic scenes, it is understandable that it's not majority's favorite genre. But for me, I really liked it. The movie didn't make me bored at all. It gave me this fluffy feeling in my heart after I watched it. Lovely! Oh, and the soundtracks were all great too.