What You Need: Film or Digital
In some ways, there isn't really a choice to be made: you use whatever you have available. If you have a film camera, use that; if a digital, use that. If you have both, then its the classic "it depends".
The debate between film and digital has been long, and in the last few years, people have voted with their wallets for digital. For most general photos, its purely a matter of preference, with both producing reasonable results from the same settings.
With fireworks, things are slightly different. I have tried to take fireworks on digital with settings that I know work 100% of the time on film - and the results were plain awful! The digital sensor is more sensitive to the bright light of fireworks, and has a tendency to overexpose the centre of each trail.
For example, a normal single chrysanthemum burst would expose well on 100ASA film at f/9.5. However, the same shell photographed on digital with the same settings overexposes. A good working exposure on the digital for the same shell may be f/16 or even f/19 - double the f number (1/4 of the exposure).
There are a couple of possible explanations; first, digital does not suffer from reciprocity failure unlike film. Reciprocity failure is the decrease in sensitivity to light experienced during long exposures on film. Usually the rule of thumb is that an extra 50% exposure is needed to counter reciprocity. However, firework exposures are rarely longer than 4-5 secs, and the object you are photographing is the bright firework. I think this is probably the least likely explanation.
The second, and although I have only heard it as a rumour, seems to tally well with my experience. Apparently, fireworks give off a reasonable amount of their light in the ultra-violet. Although our eyes, and camera film, are not sensitive to this, digital sensors are in both film and video cameras. Hence without filters to reduce the ultra-violet, a firework will overexpose with light that you would not see on film or with your eyes. This I feel has some mileage as an explanation, since whenever I see overexposed digitally-taken fireworks, there is a strong blue/white component to even red coloured fireworks.
The solution to this problem is to use a smaller aperture (although there are some fireworks that will almost disappear if you don't correct back on-the-fly), and/or to use an ultra-violet filter. I personally adjust the aperture - partially because a UV filter for each of my lenses would be very costly.
[05-May-05] Latest idea is that the overexposure is an overloading of the sensor in the Infra-Red. Whichever it is, its a problem to be aware of.
Fundamentally the choice is up to you - you can get good results from both film and digital. As said before, I use both, and occasionally both during a single display.