I saw it and it's not a sequel. It takes place in Havana in the 1950s (when Castro is taking over). It's the same basic story line (upper-class girl meets street boy, they dance, her mother doesn't approve, they fall in love) as the first one. It has nothing to do with the original movie. Patrick Swayze is in it as a dance instructor, but he's not Johnny Castle, he's just a dance instructor.
The dancing wasn't nearly as good. There is one scene with the boy lead (Diego Luna??) is dancing in the street with a bunch of other people where he looks YUMMY, but the couple just didn't have the moves or the chemistry of Johnny and Baby.
JMO, anyway.