It's a question I have been asking myself for quite some time. The key to making a great, critically pleasing film, is one that has all the right ingredients, such as good script writing, good acting and a protagonist that is developed enough for you to care about them. Critics are not likely to like a film that fails to perfect this formula effectively, whilst a casual audience member might be more willing to look over a lot of these, if not notice its flaws at all.
I think generally speaking, great movies are objectively great, but whether that movie is liked is up to the eye of the beholder. There are definitely movies that are objectively bad, that are not meant for critics, but just like it is the other way around, that does not mean that the film is not at least enjoyable.
For example, Armageddon is a really really dumb movie. How is it harder to train astronauts to learn how to drill, than it is to train drillers to be astronauts? It's an objectively bad movie, but one that I am willing to overlook for being downright entertaining. There's clearly passion put into the project, and is so much more honest about what it is than Michael Bay's later filmography, and it doesn't pretend to be for critics.
And then there are, I am going to admit, some pretty boring, by the numbers movies that just so happen to have good character development, good writing and good acting, that will get all the Oscar buzz. That's an objectively good movie, but that doesn't mean I wouldn't rather watch a dumb little escapism, if I feel like it.
Sometimes, however it isn't always as black and white, and critics do sometimes derail movies that a lot of people enjoy, and that might actually be a pretty well made movie. Sometimes, you have to remember that these critics will watch hundreds of movies a year, and when they see the same clichés for the umpteenth time, they're going to get sick of it, even if a casual moviegoer probably won't notice it, and will probably just enjoy it anyway.
So, in summary, I'd say that film is generally pretty objective, when it comes to its quality, but if it is enjoyable, and worth watching is very subjective!