I guess you could consider it one of the big 5 monster movies and include King Kong and Godzilla, which we also watch every year.
It's available at Youtube with embedding disabled or via Vimeo with foreign subtitles:
Frankenstein by James Whale 1931 from Ezequiel Lavaca on Vimeo.
1000 Misspent Hours says,
More than any other Universal horror film I’ve seen, Frankenstein displays the influence of the German expressionist directors of the silent era, and Whale made a smart move in borrowing from F. W. Murnau’s bag of tricks.Stomp Tokyo says,
Frankenstein is a classic not only for its age, but more importantly, for the fact that the film stands up to the test of time. A provocative story crafted with the genius of legendary film director James Whale, an extraordinary, pathos-ridden performance by Boris KarloffClassic-Horror.com says Karloff
adds a depth to what could have simply been a lumbering hulk (and probably would have been in the hands of a different actor). The pathos he inspires in his introductory moments is nearly Shakespearean - and all without a word.DVD Talk talks about the "greatness of Boris Karloff's pantomime characterization," saying "It's the most subtle, most human and most philosophically profound of the Universal monsters." Rotten Tomatoes gives it a score of 100%.
10/24/2009: The Husband picked this as the first in a double feature for this afternoon. The Mummy was next.