Do the opinions of critics really matter more than anyone else's
Some of them, yeah, they really do know the subject matter.
Others are just really, really good at convincing other people their opinion matters (whether they actually know what they are talking about or not).
In general, as far as how much weight you want to give anything any sort of critic says you just kinda have to go with your gut and what you already know. And with creative things in specific, it's generally OK to be like "Yeah, well your opinion doesn't count."
Not critics in general. A random guy offering a review of something doesn't necessarily know more about the topic he's analyzing than another random person. For example, not every movie critic knows all that much about how movies work on a professional level and some of them only offer personal opinions about "what they like and what not" and not about what works in the movie and why in the context of the movie and its creation. A bad critic tells you what happened in the movie, but not what it means and how it works.
Professional critics however usually know much more about the topic than random people. Some of them even know just as much as the people who created the movie (if we stick with the movie example) and sometimes they know even more and can point out things that were done wrong by the creators. You'll notice how much a critic knows about what he's analyzing by his explanations. A good critic can explain why something works or doesn't work and even how something came to be the way it is, because he knows the background of its creation and can see the methods and strategies used by the movie makers. I'd value those professional opinions much more than the opinions of random people who just watch a movie for entertainment and like it or dislike it purely based on their feelings.
i don't give a damn about what they think, though
The thing is if that person is knowledgeable on the subject matter. For example:
Back in 2005, Rob Schneider complained that another reviewer who didn't like "Deuce Bigalow: Male Gigolo" wasn't qualified to review it because he didn't have a Pulitzer. In response, Ebert wrote, "Speaking in my official capacity as a Pulitzer Prize winner, Mr. Schneider, your movie sucks."
To further complicate things, there are some things that can be criticized even if the person doesn't know anything about it. For example, I don't need to be an expert in order to tell if food tastes bad.
You also need to be able to look at things objectively, but you don't have to be paid to know how to do that.
So yes, their opinions usually hold more weight.