Star Trek IV is considered by some the last episode of the so-called "Star Trek Trilogy". The trilogy consists of the movies II, III and IV, which are linked plotwise. In order to know what the beginning is all about, you should watch parts II and III first.
The film is directed and partly written by Leonard Nimoy, better known as Mr. Spock. He also directed the earlier Star Trek movie.
It's entertaining, I give it that. We get a very unlikely but interesting plot. An alien probe has come to Earth, communicating only with the songs of the extinct-in-the-23rd-century humpback whales. The signals the probe sends are so powerful that they're ionizing the atmosphere and threatening all life on Earth. Kirk must go back in time to get some whales.
|The time travel sequence feels pretentious.|
Well, end up in the 1980's, it seems, and this is the best part of the movie. Although it's the ancient alien-in-a-foreign-land scenario, with very basic jokes, it has a lot of entertainment value. Kirk and his crew all try to act like 1980's people and go through all sorts of troubles before eventually getting back to 23rd century.
|Kirk & Spock seach an 80s San Fran for humpback whales... They should've just beamed up a KFC.|
|Kirk thinks spock did a little too much LDS in his Berkeley years.|
Then it basically just ends. The ending seems elongated and still it doesn't have any content. You just get some whale singing and some boring, predictable stuff happening very slowly. And while it lasts you'll begin to feel that's all there's going to be to it. And that's how it is. The interesting questions left at that moment, like "who sent the probe", or "what the fuck were the whales talking about", are all left unanswered. It's one of the most disappointing endings I've ever seen on film.
|PROTIP: You can skip over this part.|
OK. It's just a movie. Just quite stupid that's all.
I give it two stars.
Here's the imdb link and a trailer: