Writing film reviews has always been something I do on the side, I love films and I love writing and the two just came together. It was more for my benefit to strengthen my writing on a subject I love. It's not aimed at an audience and it's definitely not there to force my opinion of the film upon anyone. If people read it and like it, it's an added bonus for me. I've always written how I feel about the film, in a way I know best, trying to avoid being one way or another with how I saw the film, just keeping it honest and interesting. But at the same time reminding people this is just what I thought, we all have different tastes in things and that's okay.
My favourite response to my writing went along the lines of "I enjoyed reading your review, but I don't agree with what you thought about the film." I liked this honesty and it also sparked interesting conversations about how each of us viewed the film. However everything I know about films is self taught, or information i've made an effort to find. I've not studied things like film studies, media or any film related course, this sometimes makes me question "Can I write film reviews if I haven't studied film?" My thoughts are, if you're passionate about something you will learn what there is to know about that subject or make a good attempt at it at least. Also if we all had the same training and background wouldn't that result in similar if not the same work from everyone, in style, angle and approach.
How we live our lives and the interests, training and source of information defines us and I think that follows nicely over to things like film reviews. Writing requires a voice, and developing your own voice as text can be a hard thing, but if you just go about writing things in a technical, standard way, most of the audience is bound to get bored or not read. You need to place something personal to the piece, your opinions count, but there is different ways you can show this.
There is a great discussion in the link to the article below questioning what critics should and shouldn't write about, overall being that there is never a shouldn't. There is many things you can talk about for a film, from plot, story, acting, to how the audience response, your ideas and thought that arose form watching and so on. However all reviews are open for discussion and never fact. I've always been told to take the angle of how I view the film and highlight points others may not have seen or notices. Like bringing something new to the table in an interesting way that will capture an audience, but not stray too far from the purpose of the piece.
http://blogs.indiewire.com/criticwire/critics-should-definitely-write-about-form-except-when-they-dont-want-to