Caveat lector. Let the reader beware. Not the book you may be looking for.
One reviewer correctly diminishes this little guide for its lack (about ten pages) of attention to the Irish language itself (see my Listmania "Learning Irish Gaelic" for 39 other resources). The other reviewer celebrates how this pocket guidebook gave so much space to the Irish culture, largely through its Hibernicisms rendering into English often many terms and ideas derived directly from the Irish Gaelic. I therefore balance the one-star with the five-star ratings. It's not the book you might expect from the misleading title, but I did find, if you can put up with the relentlessly snarky tone adopted by so many of the Lonely Planet writers when telling us foreigners about how the natives are laughing at us, an array of witticisms and invective that no other printed source could likely provide for the non-linguist...and the clueless or the un-hip reader. Don't know exactly how useful this'd prove for many, but surely it'll lead to surprise or unexpected reactions from any Irish person you corner with these colorful and off-color effusions.
However, every culture should have its own book of such insider codes to turn the tables on each other in our global village, when tourists visit our own hometowns. Fair play to ye/yiz, as the Irish'd say themselves.