I tried to watch The Towering Inferno and was promised an exciting and tense thriller with lots of suspense as a group of characters fight to survive a massive fire in an office building. Instead I ended up turning it off almost an hour in, having gotten a few shots of flame but mostly just men in suits talking about the building with no inferno, firefighters, or action to be seen.
I don't know, maybe once it actually gets somewhere things get more interesting, but I seemed to have the same problem with it as I did the 1972 version of Solaris: did they really need three hours for this film? Did they really have to spend a full hour just on exposition and setting things up. I personally felt like it took far too long and really could have been shorter, perhaps more around 10-20 minutes would have sufficed.
It led me to start wondering: just what is the best way to start a movie. The opening scene alone is a crucial part of any film, as you really need to be able to set the tone for everything that follows. You have to establish the atmosphere, set up the actual sequence of events, and introduce us to the characters and the circumstances that drive the story. There are many different ways to do this, and sometimes some methods do take longer than others.
Once Upon a Time in the West has an opening scene that takes a full ten minutes, during which time nothing happens. What makes this scene work is it sets the standard for the rest of the movie. It shows us that what we're about to see is not a conventional western, and the rest of the movie is certainly like this. However, while we only get introduced to one major character during this scene (two if you include them referencing Frank, who first appears in the scene immediately after this) it does build up the appropriate atmosphere, drawing us in through the use of sound in particular to bring the world to life so that when the action gets started we're ready for it.
Now I have often said that one of the most crucial elements to making a good horror film is never to start with the horror itself. Never open by bringing out the blood, the guts, or the knives. The important thing is to draw the viewer in. You have to get them acquainted with the characters, the environment, and build up the right sort of atmosphere.
That way, by the time the actual horror shows up, whether it's ghosts, goblins, zombies, aliens, demons, vampires, invincible knife-wielding psychos, or Cthulhu; the audience will have developed enough of a connection to the characters and the world they inhabit that the terrifying aspects of the story will leave a stronger impact than if you just occasionally startle them with a terrible effect and a bit of music.
This is the kind of area where you really ought to take your time developing things. One example I can cite where this is done really well is Alan Parker's Angel Heart. With this film, there is an eerie atmosphere right from the opening scene (which shows an unidentified body lying in an alleyway, with the heavy implication that the victim was murdered) and it gets darker as the film goes on. The plot also gets kicked off fairly quickly, but as eerie as the film is the actual horror does not reveal itself until the final moments. The fact that such care went into building up the atmosphere makes the brief amount of time we see truly terrifying part of the story all the more frightening.
Now, Angel Heart works this way because while it is a horror film it is structured as a classical film noir. With other horror stories you may want to bring in the horror sooner, but even then you should be careful. In The Thing, you have to wait about 30 minutes before you can actually see the titular monster in action, but we still get plenty of great buildup that prepares us for that moment. The whole scene at the Norwegian camp quickly gives us a sense of dread and more or less establishes precisely the bleak atmosphere we can expect from the rest of the film, since even though nothing actually happens while they are at the camp, we are left to imagine just what happened before Mac and Copper arrived.
Now this is all well and good for horror, but what about in other genres? Some of them can work very differently, yes, but in principle it's still the same deal. You need an opening that draws the viewer in, that compels them to know more, and you shouldn't rush your beginning or draw it out too much. What you need is just enough time to get the audience acquainted with the characters and environment but not too much so that the viewer doesn't get impatient for when you actually get to the plot.
To bring up Tarkovsky's Solaris once again, that was a film that definitely took much longer than it needed to in order to actually get going. That film took a full hour just to get Kelvin into space, and yet in the Clooney version, everything that happened in that hour was taken care of in the first five minutes.
The Towering Inferno, I would also say did not need to take a full hour just to set things up; when I go to see an action movie I usually expect to see... well... action. With this genre it is of course important to set up your characters but you also don't want to bore the viewer too soon. In other words you should give them a fair bit of action early on so they know what to expect. It doesn't have to be much but it should be something. The opening of Raiders of the Lost Ark, for instance, manages to set up the character of Indiana Jones as an adventurer and an archaeologist while still giving us an exciting and tense sequence which, while not directly connected to the rest of the movie's narrative, sets the tone for everything to come as well as introducing us to one of the main villains.
So, if you want to make a good movie, you're going to have to draw the audience in, make them want to see more. You shouldn't rush your exposition but you also have to make sure you don't drag it out longer than necessary, and at the very least you should take the time to establish something for what is to come during that exposition, even if it's only at an atmospheric level.