Easy answer is no, it's about as reliable as a two-legged chair. But it is very, very nice to look at so worth getting for the piccies.
Most reliable is
Complete Guide To Middle-earth by Robert Foster, which is dull to look at but very good. Even more so is anything by Scull & Hammond (partic. their biographical stuff on Tolkien) but also expensive.
The Karen Wynn Fonstad atlas is ace, as is the Barbara Strachey
Journeys Of Frodo.
If you want a freebie though, try Encyclopedia of Arda online
