I went into it expecting (as anyone would) a cornucopia of Evil Dead style over-the-top wackiness from Bruce Campbell, of whom I am a big fan-- not only of the characters he plays, but of the man himself. In Bubba Ho-Tep, it seems as though he turned his Wackiness knob down to about "2" and instead went for the subtle approach. And, hey: It worked.
His performance (and the whole film, actually) is sort of... subtly over-the-top, if that even makes sense. Maybe it's the kind of thing only Bruce Campbell (or a movie with Bruce Campbell in it) can pull off. I don't know. I wasn't previously familiar with Ossie Davis, who plays a likewise elderly and mysteriously still-alive JFK ("They dyed me this color!"), but his character was a great complement to Campbell's, and they end up making a swell duo.
I think the argument could easily be made that the film is primarily about growing old and feeling useless, resenting having to depend on others for your daily survival, and then being presented with a situation in which you can prove to yourself that you've still got some youthful fight left in you. What I found so great about it, though, was the situation itself. I'm sure that there are plenty of such "getting old sucks" movies out there, and I'm pretty sure none of them have flamethrowers or flying attack beetles.
It's undeniably a "horror-comedy," because while there are laffs aplenty, there are also monsters and crawlies and a lot of it takes place in the dark of night. Interestingly, this horror-comedy also manages to rise above the deliciously typical horror-comedy murk and be exactly the kind of quasi-serious film where, as you watch it, you repeatedly forget you're watching Bruce Campbell play a geriatric Elvis Presley. It's just really easy to be absorbed by the story (which is not without sadder moments, as can be expected from any film which deals with getting old) and accept everything that happens as being perfectly plausible.
An interesting thing to think about, after you've watched the movie: What if Elvis and JFK are simply what they appear to be --two crazy old men in a nursing home-- and none of that zany stuff actually happened? In fact, it's kind of fun to think about that as you're watching it; Some scenes will be even funnier if you imagine that they're imagining all the danger they're in.
Anyway, the movie was pretty neat, and I'd recommend it to fans of movies that are quirky, unique, thoughtful, and/or have Bruce Campbell in them.