Disappointing - especially for a Top 250 movie

Rating: 6/10 (4 January 2012)

As I'm writing this, The Princess Bride is ranked 194 in the IMDb Top 250 list with an average rating of 8.1. Considering the rating and the fact that I love fantasy, I had high expectations. Long story short - I was very disappointed.
It's not that The Princess Bride is bad. It has its moments and a unique kind of humor. But the overall impression is lackluster at best. The plot is thin, the acting is sub-par, the main characters nothing but clichés and the special effects are barely worth a laugh. Just look at those guys it rat costumes. Is that supposed to be frightening or hilarious?
To mention a few good points, the minor characters of Inigo Montoya and Fezzik are very good. Also the cuts between the plot and the frame narrative about a grandfather and his grandson are pleasantly surprising. On the other hand, the frame narrative itself is unnecessary and only exists to provide the beginning and the ending that the plot is missing.
Why do one third of the viewers rate this 10? According to my wife, she loved the movie as a kid, but was disappointed too when she saw it recently. I guess it just did not mature well.