Going to a ‘Purple Rain’ preview? Here’s what to expect.

“Purple Rain” began preview performances Oct. 16 at Minneapolis’ State Theatre, and ever since, many of those who have thronged to the stage adaptation of Prince’s 1984 film have been blowing up social media with their hot takes.

But those reviews come with caveats. For until the show opens Nov. 5, the posters have not really seen the final work. Their responses may be to things that are no longer in the musical or that have been changed substantially.

For artists, the most important thing about previews is that the show is out of the rehearsal hall and up on its feet in front of audiences.

For the creative team, which includes the playwright, director, arranger, choreographer and various designers, this is a period of fine-tuning guided in part by audience feedback.

Does a moment land? Are audiences responding as expected, like feeling sad in moments of pathos or laughing at jokes? Do the transitions work and can the action be juiced?

For the audience, it’s a peek into the creative process of the cast and crew, and what they bring to the stage. And at a relatively reasonable cost.

Previews are typically priced lower than the cost of admission for a performance during a regular run. That’s because, as a work-in-progress, the action is up as a sort of real-life test.

One Reddit reviewer, who posted in the first week of previews, called the production overlong and “a hot mess.” But another Reddit poster who saw it two weeks later, had the opposite reaction: “I believe several changes MUST have been made because it was terrific,” the commenter wrote. “Glad we drove from Ohio to see it.”

On Instagram, a self-described child of the ’80s who was “primed and ready to love” the show, said the music is “on point.” She complimented the performers but she gave some of the script changes “the stank face.”

While there are likely to be almost daily changes in dialogue, songs, transitions and choreography in addition to blocking, costumes and other design elements during previews, there are no more alterations once the show opens.

After things are fixed in place, the creative team departs and a stage manager serves as the eyes and ears of that team to maintain the show’s artistic vision.

The official opening day performance is also the one that gets reviewed by critics.

After all, the show is in pre-Broadway tryouts, and that means that all the folks associated with it are tinkering or making wholesale changes that they believe will help them best tell the story in Times Square (and, subsequently, on tour).

In Minnesota, they typically vary from two to four days at places such as the Children’s Theatre Company, Penumbra Theatre and Park Square, to a week at the Guthrie Theater and Chanhassen Dinner Theatres.

On Broadway, previews generally last weeks to a few months. Julie Taymor’s injury-plagued “Spider-Man: Turn Off the Dark” holds the record for having the most previews — 183.