I'm not going to deny that this is a great series for children. It teaches young girls that they can solve their own problems without being too dependent on other people; aside from friends. That's something to be admired.
The low rating comes from the title. This animated series has nothing to do with Spirit, the horse. The title of the series is meant for leeching off the success that was of Spirit, the movie. Honestly, if they changed the name of the series to something else - you couldn't even tell that this had anything to do with Spirit. The low rating is due to the disgust of clickbait.
If you're an adult looking for nostalgia - skip this. If you're an adult with children - watch it with them and silently scoff and roll your eyes.