Though the comparison is far from exact, the movie that The Island on Bird Street most reminded me of was Hugo. Both feature a young boy as protagonist, one who is left alone in a secluded and potentially hostile environment yet who manages to survive and to maintain hope.
But The Island on Bird Street is more stark than Hugo; it has less of the flowery, magical imagination (though it does feature some; it's just different) and more of the brutality of war. This has to do with its setting: no French train station here, but rather a WWII-Era ghetto in Poland. Though Hugo has some dialogue-free scenes, it's talkative compared with The Island on Bird Street, which is most often quite quiet and what most people would call slow (I didn't find it slow in at all a bad way--but I know that some people need a different kind of pace). As I said, it doesn't gloss over war's cruelties, yet Alex tries to keep himself positive, entertaining himself with Robinson Crusoe (which is, of course, no accidental book choice) and his pet mouse and never giving up hope that his father will return.
Spoilers below the jump.
The ending reminded me of Life is Beautiful. After all that had happened in the movie, I was half expecting for Alex's father not to return: the chances of it didn't seem very high from the beginning, anyway. But it's difficult for a hopeful story not to end happily: it he didn't return, then Alex's long-lasting hope would have been tragic rather than uplifting.
It was a very absorbing film (based on a book by Uri Orlev, by the way), one recommended to fans of period films and heartfelt-but-not-really-sentimental stories.