Maybe this is just my opinion...okay this is definitely just my opinion. But a HUGE difference I see in films like I think are just alright and films I love are all the little quirky details. THE QUIRKS!
Most indie films that I watch are the same thing, even if they have a completely original story idea. But a select few have those little quirks which set them apart. Nothing to do with the story line.
Some examples: Let's say you're filming a horror film (what I specialize in) and you have someone sitting at a table eating. Almost every film I've seen it's a normal table. But some would have maybe a picture frame on the wall in the background that gives the entire shot and scene a different mood. Or maybe a piece of leftover food with some flies buzzing around it. That little difference can give you just the feel and difference to make it something great.
Another example is maybe a quirky dialogue. Someone who is clearly depressed. But says something completely out of the ordinary...QUIRKY! Like, "I've decided to kill us both." (Bonus points for anyone who knows which movie that's from)
I am in the pre-production of a short and I know I will be adding very small details that will make the mood and feeling of the film I create something amazing. After all, feeling and reactions are the thing I strive to achieve most.
Style certainly doesn't hurt a film, but don't get too caught up in it, as it is far from the most important part. The saying "style over substance" came to mind when reading through this thread, and I think that substance should really be held at a higher esteem than style. What are you trying to say with your film? Is there something that the viewer can take away from it?
Now, I understand that not every film should be some sort of life-changing event. You try to hard, and your film can become heavy-handed. Some films exist simply to entertain.
Ultimately though, I don't think one can attribute any one thing to what makes a great film great. Art in general is far too subjective for greatness to fit into any one formula. There are many films that follow a winning formula that suck, and even more films that follow no conventions and are terrific.
What any filmmaker needs to truly focus on is what THEY would want to see. Yes, it helps to have some input, and you shouldn't completely ignore your audience (or a group of trusted friends), but who knows what great new thing you could make? And when you do, I'm sure critics and scholars and fans will argue endlessly about what really makes that movie great, but I doubt they'll ever really figure it out.
That's the prime objective, if they don't do that then nothing else really matters. They can do a lot of other things WHILE they entertain, but if they don't entertain then you have failed miserably.
I have an entire film written to showcase quirky details like that while remaining pretty flat on the "weirdness" scale. I have one film in production and two more before I get to it, but we'll see.
Okay, here's the thing -- and this is probably my opinion only in the entire universe -- "quirky" is fine, but it by no means makes up for dull scenes, characters or dialogue.
I'm gonna catch hell for this, but I'm gonna interject the name Tim Burton here. Now, I know the man is a visual genius, no argument there. But I've found exactly 2 of his movies worthy of repeated viewings. They are quirky as hell; few others even come close on that account. The visuals are incredible. And his movies bore the shit outta me. The stories are vapid, the characters are trite, and the dialogue is cliche. Yawn.
I see so much stuff like this, it's embarrassing. Start with a good script, then add quirkiness, when appropriate.
I'm gonna catch hell for this, but I'm gonna interject the name Tim Burton here. Now, I know the man is a visual genius, no argument there. But I've found exactly 2 of his movies worthy of repeated viewings. They are quirky as hell; few others even come close on that account. The visuals are incredible. And his movies bore the shit outta me. The stories are vapid, the characters are trite, and the dialogue is cliche. Yawn.
You'll catch no hell from me. It's been a long time since I saw a Tim Burton movie that I actually liked. Big Fish comes to mind. Before that, it was Beetlejuice. The rest of his movies are boring. Okay, maybe Batman is kinda cool. Otherwise...
And why does everybody think Nightmare Before Christmas is a Tim Burton movie?!
Nothing, absolutely NOTHING, will make a good film great. A great film will be great from concept to script to prepro to production to post.
The opposite is easily true though - many things can make an otherwise great film good. In other words, the are a myriad of things that can go wrong at any step of the filmmaking process that can damage a great script.