Star Trek: The Motion Picture was horribly dissapointing in most every way at the time, as I recall from watching it in 1980 (?) when it came out. It was first and foremost nothing more than a remake of an episode of the original series. Second, it has absolutely no plot to speak of beyond hang around alien life form, do nothing to stop alien life form, watch in wonder as alien life form transforms into even more alien life form. A most un-Trek-like movie. AND, it really could have lasted only about 50 minutes, which is about how long it actually is if you cut out all the stupid time spent surveying the newly rebuilt Enterprise and the grand tour of the alien.
Star Trek: The Search For Spock was the best of the odd-numbered movies. It is still a poor entry, mostly for being over-acted, but you have to love some of the things that happen. My worst memory of that movie is having the drama of the destruction of the Enterprise taken totally away by the premature marketing of Taco Bell’s glasses which included one showing “Enterprise Destroyed”.
The cross-over movie actually shows quite well the main difference between the original series and the Next Generation. In most original series episodes, you have one main plot. There are no side plots or stories. The whole show revolves around the main plot, usually resolved in some dramatic way by the main characters (with occaisional whimsy thrown in; A Piece of the Action is a great episode, and TTWT is just great TV). TNG, on the other hand, always has an A plot and a B plot, with often a C plot tossed in for good measure. As the show proceeds, you have the crew attempting some resolution of the A plot, during which the B plot results in some character development for someone on the Enterprise. In some cases, the damn show was so wimpy, you were tempted to think the B plot was actually the A plot, and with the notable exception of episodes involving the Borg, there rarely was much drama involved in resolution of the A plot (unless your idea of drama is Denise Crosby battling some alien woman with a metal “claw” on one hand in a cage … ok, ok, don’t get me started).
The cross-over movie shows the difference quite well. The original characters are dealing with a dramatic situation, with no distracting side-plots. Then we switch to the later series, and all of a sudden, bingo, A plot, B plot, relatively benign resolution of the A plot, yadda yadda.
Thank goodness they made First Contact.