My father kindly bought me a copy. I think what's really good about it is that you can see all the sites in relation to each other. It's not like grappling with 20 os maps on the carpet, or guessing with a road atlas. I think I had some fairly ropey ideas about where some places really were (still do I admit).
I think you should get one and stick it up on the back of a door somewhere. You can always tippex out the roman sites if they offend.