There are occasions in cinema where technology overcomes the storytelling aspect. Avatar was one such; going back a bit, so was Thunderball, which was so obsessed with underwater photography, it felt more like a Jacques Cousteau documentary than a Bond film. A very similar problem is present here. While the depiction of space-travel and whizzy visual effects may possibly have been groundbreaking enough, when this came out in 1979, to meriti their lengthy screen time, they are no longer worthy of extended attention. This reaches its nadir in a very slow shuttle crawl that takes Kirk (Shatner) and Scotty out to the new Enterprise. Seriously, I could have walked there faster, and can see why Chris described this as "Enterprise porn." For a film that runs 145 minutes, there's surprisingly little going on. An energy cloud is heading towards Earth; it's up to Kirk and his crew to stop it. That's it.
The film's biggest strength is that it could well be a very large-budget version of the TV series, with the characters and their relationships as strong and interesting as ever. Spock is logical (once he gets rid of the crap hair he wears at the beginning); McCoy is irascible; Scotty grumbles about the laws of physics or whatever; and Kirk is... Kirk. But that's also its biggest weakness, as this runs more than three times the length of an episode, without significant additional content or depth. Once you've done admiring the visual effects - and, while some are still solid, there are occasions where time has not been kind, and you can see the matte edges. Overall, it's a film which puts an awful lot more emphasis on style over substance, and that's the last thing you would say about the TV series. Based on this, you'd never imagine the series would still be going strong 30+ years later, though better - much better - was to come.