I am not the biggest fan of Precure, but as a person who likes the series, I never expected something like OtonaPre to ever exist. Basically, it is a "sequel" to Yes Precure 5 Go Go, where everyone is already an adult (I think the show occurs approximately 10 years after 5GoGo ended). A lot of things happened in this meantime, and almost everything has changed in the protagonists' lives because of their pursuit of their dreams.
The designs have obviously changed, and there were some that I liked and others that I didn't, but in the overall, they were good.
The animation is bad. I know that Toei is not the best anime studio in Japan, but in the main series of Precure, the animation is better. Furthermore, the CG is horrible. Precure always had state-of-the-art CG, but something went wrong on this show.
The story and storytelling were not great. Precure is a kids' show, but this one is supposed to be watched by people who watched Precure 5 when they were kids and have grown up now, so I was expecting for something more of it. Furthermore, there were a lot of "convenient" moments that were so poorly prepared that they broke my suspension of disbelief.
So, should you watch this show? I think you should if you have already watched Futari wa Precure, Futari wa Precure Max Heart, Futari wa Precure Splash Star, Yes Precure 5, and Yes Precure 5 Go Go. The ending is good and makes you believe that it was worth watching 12 episodes of it.