Ask me how to create a good story, and I'll tell you create a Protagonist I can relate to. Ask me how to create a great one and I'll say, make sure I can relate to the Advisory too.
This movie has this amazing element. Although it's not an easy task to create an Advisory people can relate too. As oppose to other "enemies" in the previous movies / TV series who were in fact bad entities, this movie does not have any "bad guy". Oh yes, there are fights. But the greatest fight is within the audience, who must fight the question is what the advisory attempt to accomplish is really bad? Had I have the option to do the same, would I act differently. (I still not sure I have the answer).
As for the rest of the movie, as oppose to Adventure Tri, I think 90% of the movie contained an interesting events, or a build up to a conflict. I enjoyed watching it, and that what I did. I didn't feel an urge of checking my phone or fast forward.
It's nice to see the heroes you grew up with straggling the same issues you straggle now, well maybe not exactly the same things... It reminds my a little bit the Pixar movie Inside Out, where they objectify the feeling and thoughts into physical beings. This movie did the same with the tools, the people and the relations that were craft for 20 years, and the result is great.
Bottom line, if you watch it, you'll enjoy it (assuming you are 15+ years old so you can relate to the characters).
If you know the backstory of Season 01 you will really enjoy it. (the last episode of season 2 is also worth watching before heading to the movie, but it's not mandatory).
The only thing that bothered me however, was the post ending. The ending was fantastic, amazing a seething emotions were outburst, but then there was another scene which the only purpose (I think) was not to leave the audience with such a bidder taste. I saw a similar thing in the movie Your Name movie where there was an additional scene to give a little bit of hope to the audience. I really don't like this, I want a story to make me feel strong feelings. Even if they are not happy feelings, it's better than shutting me down.
Please don't let this last comment discourage you from watching this movie. It's really good, just stop in the ending (it's very obvious when the movie really ends).