Don't agree with Jim Lad - a fair and balanced review by somebody who knows and respects the subject is not only acceptable, but highly desirable, both from the point of view of the artist and of the listener.
The folk world tends to have wrapped itself in a cotton wool cocoon of first name sycophancy, which has much to do with the threads on standards which are a constant feature of on this forum.
Having said that - nasty experience coming up.

About eight years ago a review of a very important published collection of songs appeared in a highly respected internet magazine.
The review was enormous (can't lay my hands on it now as it seems to have been quietly removed from the magazine's archive) but it ran well into the equivalent of around ten pages.
There was a roar of disapproval of the self-indulgent, self-promoting nit-picking on the part of the reviewer, including a letter from me.
Two of the direct results of the review were
a    The author decided to leave the rest of his family's collection on the shelf, thus depriving us of a very important body of songs and research.
b    Following the row, lines were drawn and positions taken, thus preventing a balanced review from appearing.

Some time later we issued a collection of our recordings on a double CD with similar results from a different reviewer (in the same magazine), who just happened to be a friend of the first reviewer.
This time the review ran to 8,467 words which included 51 footnotes.
The reviewer totally ignored the dozen plus singers, apart from insulting three of them, did not discuss the quality of the singing or of the songs, but rather, nit-picked his way through the notes, leaping on every spelling mistake, perceived or real, and challenging well-established facts. He even challenged references to alternative versions of the songs we had selected, inserting his own preferences.
Luckily he was unable to inflict any long-term damage and the album now ranks among the best-sellers of traditional singers.
From our point of view;
a    It will be a long time before we consider such a venture with the rest of our collection
b    Personally, we have been put in a bloody awful position regarding the familys, friends and neighbours of those singers (mostly all dead now) who were either insulted or ignored by the reviewer.
c    One of the singers an elderly farmer who was described as "sounding like a woman", had a large notebook of his, and his family's songs which it was always our intention to borrow and copy, thus adding a hundred plus songs to the local repertoire - we no longer feel in the position to do this.      
As far as the reviewer is concerned, he is what he is and I don't suppose he is able to do anything about that, but surely the magazine editor should have exercised a little more responsibility and thought through the implications of such a piece of work; if for no other reason, at least out of respect for the elderly singers who had been generous enough to allow us to record their songs and stories, and who NEVER should be drawn into the dog-fights that sometime take place in the folk world.

As far as I'm concerned, done properly, a good, knowledgeable review can be the tuning fork for what we do and listen to; if the tuning fork has a crack in it, we all end up singing out of tune.
Jim Carroll