F-1970 stars the one and only Boris Karloff who plays the last of the Frankenstein clan. He is wonderful in this role and steals the scene every chance he gets [which is often]. Director Howard W. Koch [Airplane, The Odd Couple] also brings out the playfulness in Karoff's performance and gives the film an overall subtle sense of comedy that serves this film well.
Where this film looses its stream is when the monster appears on screen. It is utterly ridiculous and looks more like a Mummy than a proper Frankenstein. It's so bad that it drags the quality of the film downward. Granted they only had a budget of $110,000 to work with but surely they could have done better than this. A decent Halloween mask would have been a better choice than what they came up with.
If you're a Karloff fan then you definitely need to see Frankenstein 1970 solely to watch the master at his craft. If you're not a fan there are definitely better Frankenstein pictures to watch and you might want to choose one of those.
For more info check out the film's entry in IMDB.