That's the question I was asking myself as I watched it. Now, I know that it is a pseudo-sequel to the much-better and more coherent Purple Rain and it showed, especially with all the motorcycle trips out to the "graffiti bridge" (very similar in appearance to some of the lake sequences in the previous movie). And Morris Day and the Time are around again. That's really where any comparision ends.
Prince's character is hyped-up on spirituality (which of course, isn't popular with the club crowds in the film). But ever other spiritually-themed song is followed by one that is much more sexually-charged and with little if no connection to the theme the character is trying to get past. The phrase "in the Temple" is used way too often in way too many of the songs, and is often the only religious link in any of the tunes.
This movie seems to reflect the quagmire that was inside Prince himself at the time...He was trying new things but very disjointedly. The New Power Generation had replaced the Revolution, and there are many occurences of the symbol that would become his name (at least early forms of it).
The highlights of the film for me were the performances of Morris Day and the Time, Mavis Staples, George Clinton (even though he seemed to be performing a Prince tune instead of his own work) and the short dance number by Tevin Campbell.
If you like Prince, take a gander at the film...just don't expect Purple Rain. If you don't like Prince, don't bother.