"Better" is in the eye of the beholder. A movie is both a collaborative effort and the vision of a director – a good director can work from a bad script with top-notch actors, a good editor and a fantastic cinematographer to make an entertaining movie… Or they can make a bad movie. So, you can evaluate the movie as a whole or you can look at the elements that make up the movie.
To me, three of the earlier Star Trek movies are great movies, full stop, where all the elements just click and work. They also happen to be Trek 2, 4, and 6 – which is where the famous "only even numbered Star Trek movies are good" cliche came from. I also think that the new reboot/sequel/prequel Star Trek is a great movie, where everything (well, except some of the contrived plot points that "brought the crew together") worked. The fact that no one viewing the movie had to have any knowledge of the original show was also a major reason it was successful… But that's not the question, so…
In summary, I'd say it's not better, just a different take on the material that worked very well. Most of the original movies are just as good… But just not all of them are (again, look for the even numbers).
And of course, Star Trek II: the Wrath of Khan is the Citizen Kane of Trek. This is an absolute fact that cannot be denied by any sentient beings who appreciate Star Trek.