This article is from the rec.music.reviews FAQ, by Al Crawford (firstname.lastname@example.org) with numerous contributions by others.
That depends on who wrote the review. Posting a self-written review of
your own release would be frowned upon, since it's likely that you
wouldn't be the world's most objective reviewer, but if your release
has been reviewed elsewhere by somebody else, and you have obtained
permission from them to reproduce their review, that's fine. If you
want to post a self-written review, you'd probably be better off
reclassifying it as a very descriptive release announcement and
submitting it to rec.music.info. The above also applies to agencies
trying to promote an artist by posting promotional blurb that looks like
reviews. This is a definite no-no, since rec.music.promotional exists
for exactly this purpose.