Amazon have linked this review to the 2008 Edition as well as the 2004 one, so I am expanding the review to include both Editions. Don't buy anything except the most up to date edition.
2008 Edition (Village with painted houses on cover) Review.
Two editions later my review title from 2004 still works pretty well: This is the best laid out Guidebook going, with Lonely Planet's trademark plans of towns, villages and popular sites with all the places of interest, accommodations , bars etc show. There are excellent contents pages at the front to take you to the place in Ireland you want to get to and a good index at the back. There are short Irish history, culture etc sections to give you a feel for the country at the front. All the technical stuff: how to get to Ireland, insurance, visas etc is at the back.
This edition of the guidebook is more streetwise. Its writing, previously pretty anonymous, has aquired a relaxed modern Irish feel that makes it a lot easier to read through. There were seven researchers working on this edition, and it shows. Time and again this Guidebook goes the extra distance and gives you useful nuggets of information that will make you trip easier, more enjoyable or both. However, in order to provide more information on main tourist destinations some less popular places have been left out. The Guidebook is not as comprehensive as it used to be.
Despite all those researchers some information is as much as five years out of date, but overall this is now (as of early 2008) the most up to date Guidebbok to Ireland for budget travellers.
It is now completely internet friendly with web addresses all over the place.
While not being perfect this is as good as Guidebooks get. Take it out in any tourist location around Ireland and it is the nearest thing you will get to having a local person show you round.
2004 Edition (Shamrocks on cover) Review.
This guide is packed cover to cover with information in an easy to access style. Best of all are the many town maps which mean that the location of everything, from the Post Office, to the Banks, to the Bars and Accomodation is clearly laid out before you. The county by county coverage is pretty comprehensive, but with a few ommisions of smaller places that could have been included.
Since the last edition the guide has become fully web friendly, with website and email addresses included wherever possible.
As for the comprehensive nature of entires and how up to date they are, I am a frequent user of hostel accomodation in Ireland, so I can best judge by that. Coverage is in general good, but can be a few years out of date in some places. Also the choices of places in some major destinations is a bit idiosyncratic.
Overall however, an excellent guidebook that gives you the information you need when you need it.