I had read some of the bad reviews before seeing Jonah Hex, and I'm honestly not sure what those moviegoers were expecting.
Jonah Hex is a very entertaining flick, and will appeal to 3 groups of movie goers. Those that like action films. Those that like comic book films, and /some/ of those that like westerns.
It's not the worlds greatest writing, but no action film ever is. It is simply a highly fun run through DC's version of the end of the old west.