This book aims to teach Homeric Greek to people who don't have any background in any language other than English—that is, it's not a supplement for people who already know the typical Classical Attic, but it's an actual from-scratch course teaching Homeric Greek in the same way a normal language is taught.
This is, of course, an absolutely bonkers idea for all the obvious reasons, including the fact that Homeric Greek was never a spoken language, that turning Homeric forms into paradigms means creating forms that not only didn't exist, but often couldn't (because they don't fit into dactylic hexameter), that Homeric Greek's multitude of linguistic strata means that a lot of slots in paradigms will have a multitude of alternative forms (and this variety is never explained, it turns out), and that every other work out there presupposes familiarity with Attic, so any wretch who struggles through this will have to unlearn and then relearn a ton of stuff if they ever want to engage with the broader academic community.
(There actually is a four-page introduction to Attic Greek included at the end of the seventy-seven lessons, but it's slapdash and inadequate, several times giving up on explaining a concept and telling the reader to "see any good Greek grammar" instead.)
Perhaps you don't care about Greek as a language and only want to be able to consume the Iliad and the Odyssey shallowly as fun little stories without having to know about their history and manner of composition, though (after all, there is precedent for people learning a specific dialect of Greek to be able to read just a single text: certain breeds of (American) Protestant learning just Koine for the New Testament)—will this at least help you do that? Not even really that.
As someone who learned (Attic) Greek from zero not that long ago, I do have a number of didactic quibbles with the generally old-fashioned approach taken by Pharr and his successors, but those really are just quibbles and obviously the fundamental approach taken has worked adequately for many decades in teaching Classical Attic. More serious is the fact that key concepts just aren't explained fully or correctly, including dactylic hexameter itself: that gets five pages that contain just enough information to scan the first two lines of Iliad (including the concept of synizesis, for Πηληϊάδεω) and then direct the student to scan more on their own without so much as a suggestion that e.g. Attic or epic correption exist. The reference grammar does contain the most laborious formulation of Attic correption I've seen yet† in the phonology section for some reason, and epic correption is finally mentioned very briefly (blink and you'll miss it—I was looking for it and I did on the first pass) one hundred and ten pages later in the prosody section; neither phenomenon is given a name.
Not many people end up using this course, alhamdulillah, but if you frequent the sort of online forums where people sometimes come for help with Greek, you'll inevitably run into at least one; as far as I can tell, everyone who does use this course ends up confused and with tons of very basic and often reasonable questions the book can't begin to answer.
And on the topic of the reference grammar: that makes up about a quarter of the book and you might be forgiven for hoping to extract some value from that. Unfortunately, it's constructed purely to support the lessons, not to stand on its own or provide the sort of information you might want as someone who recognises Homeric morphology as worth commenting on. Pharr also had yet to join his contemporaries in the 20th century, somehow, and his successors have made no attempt to bring any of the terminology into the 21st: expect gutturals, smooth and rough mutes, improper diphthongs, first and second aorists and perfects (alright, those are still current in some places), and lots of circumlocutions because the word "sonorant" apparently hasn't been invented yet. (Of these, "mute" for plosive is the one that never stops annoying.)
On the rare occasions this part of the text does dip its toes into trying to explain why a thing is the way it is instead of just listing the thing, it often takes a turn for the bizarre, such as when it "explains" the accentuation of πατρός and πατρί by pointing to the rules of accentuation for monosyllabic nouns (which "regularly" get the accent on the ending when they turn disyllabic in the oblique cases; broadly true, but the many exceptions aren't even hinted at) and claiming that πάτηρ [sic!] was originally the monosyllabic (!) πατρ̥ (!!)! Apart from anything else—two centuries of comparative Indo-European linguistics, that is—what do you think that ring means, Clyde Pharr?
Shockingly disappointing. I had hoped to use this book to support the Greek Epic Lit class I've got this semester, but I'm going to have to look elsewhere.
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† If a mute, [sic] followed by a liquid, or by the nasals μ or ν, comes after a short vowel, and the mute and liquid (or nasal) come within the same word or the same part of a compound, the syllable is common, that is, it may be either long or short, according to the requirements of the verse.