There are a lot of wax figures, many of characters from his movies (like the pale man from Pan's Labyrinth pictured below), though some are from other films or actual people. In a few cases there are blank forms showing off costumes, as with some of the dresses from Crimson Peak.
There are a lot of pictures and paintings and small sculptures. Two of my favourites were this miniature, "The Captain's Bed" by Teri Hardin, and reproductions of two of the skeleton warriors Ray Harryhausen created for Jason and the Argonauts.
While I've not seen The Strain, I greatly enjoyed seeing the inspiration pieces, some props, and the gorgeous angel of death.
One of the last rooms has a couple of Frankenstein wax figures, along with more creepy artwork.
If you like monsters, the macabre, movie props/memorabilia, or Del Toro's work it's a fantastic exhibit. It took me over two hours to go through (though I was taking a lot of photographs). There's a wide variety of objects to see and an interesting glimpse into a director's mind.