It can be seen online at the Internet Archive or from GoogleVideo:
an interesting locus of the themes that had been popularized around the time. It features several of the famous names in horror of the era – in particular Lionel Atwill and Fay Wray.1000 Misspent Hours says, "And make no mistake, The Vampire Bat is definitely noteworthy, even despite its obscurity" and closes with this: "With a busier script and some leaner, more natural dialogue, this movie could have been a bona fide classic." Classic-Horror.com concludes:
When we watch modern horror films, we know that ... there is also genetic material from the little films, the scrappy unsung independent films like The Vampire Bat, that took from the greats and then refined what they took and made it better or at least different.TCM has an overview.