Saw it a couple of weeks ago. This is one of those films that sounds MUCH better on paper than what you actually see on film.
Campbell was great, and the backstory of him as Elvis who switched lives with an impersonator was enough for its own movie. That's where all the cleverness was, the mummy seemed just thrown in to make people snicker when they told someone else what it was about.
"Dude! Bubba Ho-Tep! Bruce Campbell as an elderly Elvis Presley fighting a freaking mummy with his walker!" See that just sounds funny. Not so much when you see it.
And they obviously weren't entirely confident in their gimmicky premise, a sizable amount of time is spent on a subplot centered around the puss filled tumor on Campbell's penis and whether or not a supernatural whodunnit is thrilling enough to give him an erection. Nice.
It had its moments, but if you see Bubba Ho-Tep, make sure you're REALLY in the mood, that and a good crowd can make it kind of entertaining. Otherwise thumbs down.