The plot is supposed to be the Mummy's revenge as he travels to America in search of those who did him wrong in the last film. This is actually a good premise but it's executed poorly. It would have been much more interesting to have Kharis shamble down the streets of NYC, terrorizing tourists everywhere. Universal settles for the back lot of the studio because its cheap and easy.
Yes, the cinematography is fine but the Mummy himself looks a bit worse for wear in this film. Not scary at all. It is some of the worst make up the legendary Jack Pierce ever conceived. [I guess everyone was on auto pilot for this flick.] Stay away from this one unless you're a real fan of mummies. It smells like a studio trying to make a buck on a budget. [Apparently they succeeded because two more sequels were made after this one.]
For more info check out the film's entry in IMDB.