I used to read this and think it would be so fun to go to a tropical island with Lars and the Boxcar Children and live on sea biscuits.
I still find it a very good book. I'm not sure what the other reviewers mean about its being slow at the beginning - every story has to have a beginning. You can't jump into the action without a bit of setting or you fall flat. Anyway. I didn't find it slow.
I recommend it greatly, especially if you like stories of survival on remote islands.