So far, having only used this atlas a few times, I have discovered 2 critical errors. While I felt that the map was detailed and the design well done, changes that have been made to roads even before this atlas was published and inaccuracies can be frustrating or even dangerous.
The first problem. This atlas has not been fully updated to reflect changes in roads, even road changes that were made before it was published! For instance, Castle Hot Springs is a place that is north of Lake Pleasant (p. 43 of the atlas). The road to get to it, Castle Hot Springs Road, is a 2-lane, paved road with wide shoulders on either side. If my memory serves me right, this road was there before the atlas was published. According to the DeLorme atlas the roads that go south from the springs and north to it don't even meet- by a margin of three miles! Moreover, the parts of that road they do show indicate that it is no more than a roughly-graded dirt road- not a paved hgihway. Check GoogleEarth if you want to see for yourself.
The second problem. The different "lines" that the DeLorme has used for the roads in this atlas are inconsistent in how they are used. For example, the ride between Prescott and Crown King is pretty rough- no guardrail (sheer drops 100+ feet), unimproved dirt roads, a 4WD vehicle required. Even with an experienced off-road driver, the ride is limited to 5 mph in places and averages only 15-20 mph. However, the atlas shows that the road improves around Goodwin into an improved dirt road. The same kind of line is used on the forest road north of Payson, AZ where you can often go over 40 mph safely. Needless to say, I'm writing this bad review because of that. The road after the place called "Goodwin" was worse in many places. At one pint, the road had an extremely steep, angled part which we barely made past in a 4WD Explorer. We saw compact cars doing 40 on the forest road near Payson.
To add a bit of insult, the same line is used outside of Crown King on the way back to I-17. We averaged 35-40 mph down that road.
Needless to say, this atlas needs to be updated. Despite the economy, development has changed roads in Arizona a lot since 2008. However, it appears with this atlas material errors were made in representing features that existed before 2008. If you buy this atlas, understand this fact and before you go anywhere you are completely certain is 100% safe, do your homework. Though, I'm sure there are more accurate atlases out there.