There are many elements that can make up a good film, from the cinematography to the narrative and even the editing. All these factors make affect the quality and entertainment of a movie. 

A good film is one that uses these factors to make an interesting story using a range of artistic and technical ideas to both look good and be able to uplift the intended narrative. For example, if a film is beautifully written but has incredibly lackluster editing choices the film may be boring or even unwatchable from strange disruptions to the pacing and tone. A great concept is easily ruined by a few poor decisions, even simple things like timing or a small handful of awkward performances.  

A bad film is arguably one that fails in many critical areas, like an incompetent director, poor studio management or budgeting difficulties. These all impact how a film is treated behind the scenes. A film could also be considered bad if it has bad intentions going into it, like making the film specifically to make money or making it to spread a harmful message.  

Some films might be disliked by most audience members when it first comes out but then become relevant a few years later, after finding its perfect audience or the social issues discussed in it are more relevant to a contemporary audience. A film may not exactly be bad but just ahead of its time. Some other films might also not find a lot of box office success but may still have a higher artistic value than what is doing better financially. Whether or not a film having a higher artistic value makes them “better” is up to the individual film and if they use these aspects to enhance the story or if they just do it to be unique. 

There is also the concept of how rewatchable a film is and if it gets better if one rewatches several times over. A movie whose main concept revolves around a plot twist, like a murder mystery, may have less rewatch value as so much time is spent setting up something the audience already knows. There are also older films which, when rewatched, can give the viewer nostalgia, especially if the film was a part of their childhood. Some newer movies even set themselves around an older time to cater to nostalgia and get more people to watch it. Some older films may be seen as worse by modern audiences because of a change in societal attitudes around certain subjects and issues and seeing them being seen in that way may be offensive or upsetting. 

In conclusion, what makes a good film is incredibly subjective however I personally prefer films that use their artistic and technical abilities to elevate an interesting and engaging story.