Harold Bloom appears to have done little work and put very little thought into this collection of "Modern Critical Interpretations" of Tolkien. His so-called introduction is barely a page long and says nothing of the history of Tolkien criticism. He does not even explain why the included articles were chosen (and there are no introductions to individual articles either). In truth, his introduction is so short, supercilious, and devoid of substance that I do not believe it to even be a sincere scholarly effort-- it more has the character of something that was dashed off in 10-15 minutes.
Nor is a significantly greater effort evident in the selection of articles. The ten articles republished here are all 20-30 years old (written between 1968-1982) and do not reflect current (or even recent) trends in Tolkien criticism. That's not to say that they're bad or completely irrelevant, mind you. However, they are starting to show their age (especially the older ones, like Roger Sale's article and Paul Kocher's contributions, as well as the Jungian approach to ciriticism evidenced by the excerpt from Tim O'Neill's _The Individuated Hobbit_, and Anne C. Petty's application of Joseph Campbell's _Hero with the Thousand Faces_ and Vladimir Propp's _Morphology of the Folktale_ to Tolkien's fiction. Again, it's not that these are bad per se, but the kinds of approaches and methodologies they represent are pretty much passe-- both in literary criticism in general and in Tolkien studies in specific. They make some worthwhile observations, but they just seem old, tired, and a bit too well-worn. The one exception to this is an excerpt taken from Tom Shippey's excellent _The Road to Middle Earth_, one of the most recent works to be reflected here (published in 1982). In short, the essays included here have OK substance, but it's not entirely clear why Bloom chose such old ones-- or whether these were even the best old ones to choose.
All in all, there is enough substance in these old articles to interest a Tolkien fan or scholar in spite of their age-- however, don't expect a lot (or in fact, any) insight from Bloom himself on Tolkien's fiction or on the history of Tolkien criticism, because it just ain't there.