Attack of the Giant Leeches, co-produced by Roger Corman and his brother, is a 1959 monster movie that comes in at barely over an hour.
from Internet Archive:
1000 Misspent Hours has a negative review and seems not to find anything good to say about this one. ClassicHorror.com has a positive review, saying "it celebrates all that’s funky about B-level creature features.".
5/31/2009: Radiation Cinema has a review.
7/10/2009: Classic Sci-Fi Movies blog has a review.