This Hammer "Frankenstein" film is undoubtedly the most graphically violent of them all, and I believe that’s where its shortcomings originate. Essentially, it feels like a retread of previous versions; there's nothing left to be inferred. Peter Cushing, portraying “Baron Frankenstein,” delivers some dialogue that adheres more closely to scientific principles, but Shane Brent in the role of his capable and scheming assistant doesn’t contribute much beyond being visually appealing, which also applies to Madeleine Smith as "Sarah." A point of interest is David Prowse's appearance as the creature, prior to his later well-known role. After receiving the brain of a professor, the monster observes himself in a mirror and understandably becomes somewhat upset. The production quality is good – it was Terence Fisher’s final film – but presently it functions as little more than disposable entertainment.

Source on TMDB