This episode reveals the depth of Mr. Howell's greed and control over others. Although it is portrayed in a hilarious manner, Thurston actually has both Gilligan and Lovey serving him as slaves in the goldmine (although he did say he was paying his wife minimum wage).
One of my favorite gags of Season One is when Gilligan and the professor are underneath the life raft while patching it. Mr. Howell calls for Gilligan. Then out pops Gilligan's head next to the professor's legs. Mr. Howell is convinced Gilligan is a master contortionist. It is rather convincing when Gilligan decides to tie one the professor's shoes!
The icing on the cake for this episode is the fact that it is not Gilligan who botches the castaway's attempt to leave the island. He is the only one who does not sink the life boat with a secret stash of gold.
With that said, I give "The Big Gold Strike" an above average rating of 8.4.