I used this map to plan and execute a drive through Isaan, mainly on major roads. It is a useful overview to what we can expect to see along the way, including cities, the largest of the towns, and some sights along the way.
I am writing this review for balance on the other two reviews, particularly the one-star review which does not seem balanced to me. I am giving it 3 stars (which Amazon defines as "It's OK" because that is closer to what I think than 2 stars ("I don't like it"). I'm glad to have it for this trip, but I agree that it would not suit the needs of someone going way off the usual roads.
The map could have a lot more details, but the next level of detail involves a large number of villages and roads that vary in quality along the way.
What I find useful about it is the atlas-style presentation of the rectangles that map this region - i.e. turning to the next page forward brings you to the next block east, and the tops and bottom pages refer you to connecting pages. Thus you can get the big picture fairly easily, and see relationships between places you might want to go. And obviously an advantage of this map is that it covers three key countries many want to visit - per the title - but also includes a similar level of detail for Laos and Myanmar/Burma when the rectangle includes them. It also includes partial maps of Vientianne and Luang Prabang, two key destinations in Laos.
Of course, it is out of date now, and won't show all the latest border crossings.
Aside from the stars listed on reviews, another view of the usefulness of out of print products from Amazon is the price. The rather high price of this item as an outdated, out-of-print map suggests that it is still in demand.
If you REALLY want details, check out maps dot google dot com, which has a very detailed map of Thailand (only) with satellite images. Unfortunately, the legends use the Thai script, but you can search for nearly any town or village listed on the map and - if you guess the spelling used on google correctly - even find it.
If anyone figures out how to get google to show Roman spellings instead of Thai, please add a comment to this review.
UPDATE: google now has legends in both English and Thai. Thus you can print very detailed maps for your planned trip. The detailed map book is still useful for navigating on the fly.