I enjoyed this at the time, but agree with others about the first 20 mins, which were a bit slow. I didn't believe the central couple as an actual couple at all, either - there was no chemistry between them.
After they landed on the island, things improved a lot, and there were some really good and inventive set pieces - especially the fishing lines and the broken bottle scene. Not sure about the kangaroo baby though.
All in all, enjoyable, but fairly forgettable.