[Nick Zwar]

A review should tell me more than if a movie a score or a book fits the critic’s brillant taste or not.

Very true. It’s ridiculous how many people seemingly feel called to write a review about a movie they have seen (on Streaming/Letterbox/Internet… etc.), but don’t go beyond “I didn’t like it” or “great” or “it sucked” or “not bad”.
It’s really not interesting that a certain reviewer likes or dislikes something, but why. A good reviewer enables me to find out whether I might like something, regardless of whether I agree with the review. I always thought Siskel & Ebert were excellent reviewers, after they discussed a movie, I had a pretty good idea whether it might be worth for me to spend my dollars and go see it, regardless of whether I agree with them. Same with Dave Hurwitz and Alex Ross, I consider both of these excellent reviewers of classical music, regardless of whether I agree with them.

A good reviewer should have:
1. A real and deep general passion for the subject
There’s no point if the reviewer has not connection to what it is that he (or she of course) is reviewing. So a film critic should have a broad and wide understanding and love for movies, a classical music critic a broad and wide love for classical music, etc…

2. A broad knowledge of the subject
That’s the next thing: experience. You can’t really be taken seriously as a reviewer unless you really know your subject. You should be able to position what it is that you review int the context of its broader field.

3. The ability to communicate well
It must be clear what it is that you say. So experience and knowledge alone isn’t enough, you must also be able to get your point across. A good reviewer is “understood”. A good reviewer communicates in an entertaining way (good reviews should be enjoyable to read/watch/listen to etc.), but is also precise.

So if a reviewer has these three, I tend to consider the reviewer good.

There’s a bonus point when I consider a reviewer “great”, but that one is subjective, so it gets an extra section. That is
4. Do I agree with the reviewer
I don’t mean always, all the time, on everything. Obviously not. But sure, I can relate better to a reviewer if I at least by and large consider many of his or her reviews valid myself in some way. What good does it do if a reviewer may fit all what I list from 1-3, yet if I almost always disagree with the reviews themselves, it probably means the reviewer and I lack some common ground elsewhere.
On the other hand, when I do think I share a lot the reviewer’s opinion, it can then be interesting to find the reviews where one differs, and perhaps see why the perspective is different here. A great reviewer may make me reconsider an opinion I have, enlighten me in some way so I might give something another shot. (Or vice versa, theoretically.)