This movie has a fairly decent premise - one gruesomely featured again and again in science fiction films, most spectacularly in "Alien" - and some decent "he-man" performances from the male cast. The possessed astronaut's wife, to me, is the weak link in the ensemble - she doesn't seem to know what to do with her face in a lot of her most prominent scenes, for which I blame director Corman.
Given a decent budget for props and special effects and a more focused and coherent screen play, "Blood Beast" might have been pretty decent. But the inherent cheapness of the production design and the continuity errors and gaffes undermine the proceedings. For instance, every time I saw the comatose astronaut laid out on an "examination table" the width of an ironing board, I broke into giggles, probably not the the emotion the crew wanted to invoke. And the monster's costume needed some serious work; fern covered parrots just aren't scary or convincing.
Still, the premise was strong enough that I hung on to the end just to see how the plot would resolve itself, and the alien's motives were sufficiently ambiguous at first that I could sort of think of it as an enigma. And the scene with the shot of the murdered scientist had a bit of punch to it, along with the plot development where the alien claimed to have assimilated some of the dead man's personality.
It's Corman. It's cheap, fast, and mildly watchable if you don't think too hard or expect too much. What more needs to be said?