My feelings about this are complicated, because while I’m a big fan of Mel Brooks’s work, I really don't care for Gene Wilder’s acting style. It's intended as a spoof, and credit should be given to James Whale along with Glenn Miller and many others whose contributions led to the script’s lively rhythm, which rarely lags. Wilder—the grandson of the scientist who inspired the story—travels to Transylvania and discovers a formula that could potentially resurrect the deceased. I think Marty Feldman deserves most of the praise for the performances, as he's excellent portraying Igor, struggling to stop the main actor’s exaggerated behavior—he seems to approach every part with the same overly theatrical style, using wide eyes and dramatic movements that I don't find amusing. Despite this, Brooks and Wilder are at their best when it comes to the writing, and as a parody, this film essentially established the entire genre—sometimes in obvious ways, sometimes more subtly—and the dialogue is genuinely funny. It would have been better with a different lead actor, but the script has aged well and remains worth seeing.

Source on TMDB