/// Wes Hemings ///
To me, writing a good review is akin to writing a good TV show like "Lost". You want to start it in shocking fashion, declaring a specific point of view that demands itself to be fleshed out and explored. Simple declarations such as "I liked Lost's series finale." is hardly eye-catching, though it is specific. Instead, "Lost's finale turned me into a smoke monster of hatred toward mindless writing hacks in Hollywood." is a bit more specific, invokes a point of view that promises elaborative answers to the implied question of: "Why did you hate Lost's finale?", and that's when you have the reader interested in your views and voice.
Once you have an opening worthy of Shakespearean tragedy, it's ideal to add any necessary background to the uninformed reader such as the breakdown of the movie/show you're reviewing, "Lost is about (and only about) people stranded on a mysterious island with mysterious powers.", it's also appropriate to include any personal history with the project, "I've wasted 6 years of my life watching, reading, talking, theorizing about Lost, so this finale is important to me.", this helps add perspective to the casual reader so they can fit in their tastes more closely with yours.
I think the most important part of writing a quality film review is removing anything that could be a spoiler, because they're reading it to know whether they should see a movie, not to know that they can claw through over 100 hours of television and walk away not being any wiser as to why Hurley won the lottery with those freaking numbers a mad man was mumbling in an institution or why food was still being dropped by the Dharma Iniative though Ben killed them years ago and if finding the island were that easy then surely Widmore would have found it long ago. So it helps to keep your views more generalized to concepts, i.e. "Lost built its franchise based on mysteries on an island that tied into the characters' past in a fresh take on converging storylines a la such films as 'Traffic' or 'Crash', yet negated to fill in the blanks that attracted viewers in the first place."
Depending on your level of film expertise there are several angles you can take when reviewing a movie. Being someone who shakes hands with acting, writing and producing I often critique a movie from several angles such as the setting, plot, characters, acting, themes, special effects, music, photography, etc, picking whatever seems most relevant. The first episode of Lost I would probably comment on how gorgeous the setting is and how I love the vast amount of characters and sheer contrast they all bring. The last episode I may focus more on how themes overrode the plot and ultimately drove writing integrity back out of Hollywood (the last I heard it was en route to Guam).
My number one rule I try and live by: no generalities, be specific as to "why". This rule must be married to the no-spoiler rule, because if you can't say why you don't like something conceptually then you probably don't have an opinion worth reading. To this end, it helps to contrast similar films to shed light on why you feel a certain way, i.e. "M. Night Shymalan is often ripped for his consistent style of twist endings that come off as flat, but at least they arrive at a promised destination, though the location may not be desired. Lost, however, booked you a ticket and left you on the runway with nothing but emotional goodbyes in the airport, the only twist we're left with is this knife in my spine."
Length is in the eye of the beholder. I keep my reviews almost always to five paragraphs: intro, synopsis, what I liked, what I didn't, outro. The opening allows me creative wiggle room to try and grab a reader, then I can set the stage for my opinions and drive it home at the end. This brings me to the conclusion: Lost is ultimately about murdering viewer intelligence via sporadic coincidences unobligated to explanations outside of using the island in Deus ex machina fashion. Wait, what are we talking about again?
/// Thank You Wes Hemings {website / blog}
