It hasn't got a great replay value, because most of the puzzles are based on item combinations (which is rather simple, really, because fitting items will flash) - only two of them (the machine in front of the house at the beginning and the - err - phone-totems on the island) require real thinking. The story is nice, the ending is fun too.
Overall, it's one of the better adventures published the last years, and it's one of the few computer games featuring characters with a little depth and psychology, no stereotypes.