This book is poorly written - because of long sentences, it's extremely difficult to read and understand; don't think that that's because it deals with difficult topics - content is extremely basic (in the worst meaning of this word) and many intricacies of this beautiful subject are completely ignored; many very high yield topics for USMLE step 1 aren't even mentioned; writing style is boring and inimaginative as well; this books is also poorly illustrated - immunology is a subject which is difficult to understand without pictures; at the same time, 'High-Yield Immunology' is extremely expensive for the number of pages and for the amount of information presented.
There are many much better reviews of immunology - try, for example, new 'USMLE Road Map: Immunology', by Parmley, with numerous well-done and useful illustrations - you'll be amazed how this author has managed to put all heavily board-tested immunology topics in just 224 pages (MCQs and index included - by the way, both these helpful features are missing in 'High-Yield Immunology'); what's more - all difficult topics are explained in a logical, clear, and uncluttered way - so different from 'High-Yield Immunology'! also, 'USMLE Road Map: Immunology' is even cheaper - by $2 - than good for nothing 'High-Yield Immunology'.
Otherwise, if you need more in-depth review, get Abbas' excellent 'Basic Immunology' - this little (336 pages) textbook is also packed with useful information and nice full-color illustrations, but it's much more expensive - $59.95.