Alfred Hitchcock was not a director with tremendous range. It worked out pretty well for him, all things considered - you could always count on stunning, surehanded visuals, outstanging narrative drive, and performances that hit just the right notes. I've often heard that Hitchcock's films aren't noteworthy for their acting, and I've rarely found that to be the case. If you put people in the right situations, they will show stress. They will show fear. They will create suspense where there is none. Being attacked by dozens of birds is one way to accomplish this (by the way, say what you want about The Birds - that's my kind of blockbuster).
Another way is to hire naturally great actors, and Hitchcock did this quite a bit. Less so when it came to women, but c'mon - Cary Grant, James Stewart, Anthony Perkins (who would be great in other stuff, most notably Orson Welles' The Trial), Joseph Cotton...and Henry Fonda. Actors capable of doing the heavy lifting without a director's help. Fonda brings natural humanity to a role that absolutely requires it, and ends up carrying the film, because for the life of me I can't see what Hitchcock saw in the story.
The problem is there is absolutely no investment. Manny (Fonda) falls into a situation that only gets worse and worse, but outside of the weariness of Fonda's performance, I didn't feel much of anything. Not even the thrill of the narrative that Hitchcock is known for. He rarely indulges in the desperation or the despair of the situation, save for the night Manny's put in the slammer (which is a really stunning sequence). It felt like an assignment for another director, and Hitchcock was merely going through the motions.