Most of the really good critics have studied film much more than the average moviegoer which is why a lot of 'film buffs' and filmmakers agree with critics on a lot of stuff because they too have studied films more than the average moviegoer. I'm not saying this makes their opinion right or wrong. Does it make it more valid? In certain cases, how unpopular this sounds, yes I do. I'll trust a doctor to give me medical advice over Joe next door because my doctor studied medicine his whole life. Its not as clear and cut as that because film is art(or its supposed to be anyway) and art is subjective. However, from a technical standpoint, when a critic says this film is edited well, or has good cinematography, I take that in consideration. If they've studied filmmaking, those 'tangible' aspects of filmmaking are a little more objective, though still not entirely.
However, the story and the overall entertainment of a film,which is what most average moviegoers go to see, is entirely subjective and their opinion has no more validity than anyone else. This sometimes, IMO, is what causes the rift between a lot of critics and casual moviegoers. Moviegoers care primarily for the entertainment factor, while the critics factor in the other 'tangible'(not the right word really, but just go with it) aspects that casual moviegoers simply don't care for. For instance, The Tree of Life was beautifully made. The acting was great. However, I wasn't really entertained, so while I have some respect for it from a filmmaking standpoint, I wouldn't say I really 'liked' it. A critic however, with my same opinion, may give it a pretty damn good review because everything else, aside from the entertainment factor, was extremely well done.
Thus brings me to Ebert. Ebert was the greatest critic of all time because he thought both like a critic and like a fan. He rated things based on the type of film it was. Its silly to think Anchorman 2 should have the same filmmaking craft as a David Lynch film. In Ebert's own words:
"When you ask a friend if Hellboy is any good, you're not asking if it's any good compared to Mystic River, you're asking if it's any good compared to The Punisher. And my answer would be, on a scale of one to four, if Superman is four, then Hellboy is three and The Punisher is two. In the same way, if American Beauty gets four stars, then The United States of Leland clocks in at about two."
Most casual moviegoers think like him. When I give The Dark Knight a 10/10, that doesn't mean that I think The Dark Knight is perfect and right up there with The Godfather. It means its The Godfather of its genre.
Me personally, I really enjoy critical reactions. I don't always agree, but I love reading a well written film review. It can praise a film I hate, or hate a film I love as long as its well written. I also personally think people take film critics too seriously. They aren't saying 'hey you have to think like me'. They get to see films early and they get paid to let people know what they think so you can decide if you want to spend the $10 on the ticket for it. Its just like asking a friend if they saw the most recent release and if its worth seeing. Like your friends, its all about following the right people. If you're an action junkie, you probably don't ask your friend's wife who loves all chick flicks, if she liked a movie. You ask your friends who have the same tastes as you. Similarly, find a critic with similar tastes and you will begin to enjoy reviews. I didn't always agree with Ebert, but I loved reading his reviews. We agreed on a lot, so when he liked something I was anticipating, my anticipation grew. When he didn't like something I was looking forward to, I lowered my expectations.
But yeah. Thats what I think about critics.