I moved to DC a little over a year ago and originally purchased this guidebook to have on hand for visiting family and friends. I have since realized that it contains numerous errors, ranging from strange judgements about DC's "highlights", to erroneous geography, to downright nonsensical advice about dangerous neighborhoods.
Just to give a few examples:
1. The guidebook refers to the area around Connecticut Avenue as "New Downtown". I have yet to hear anyone refer to that neighborhood by that name- and I spend time around both "Old" and "New" downtown. If you use it, you will get a blank stare.
2. The map-maker seemed confused about where the DC waterfront is. The Waterfront neighborhood of DC is the area around 4th and M Southwest. The map-maker shows the Navy Yard area as the "Waterfront". This is actually the Anacostia river waterfront, not the Potomac Waterfront. IT IS ALSO A DANGEROUS NEIGHBORHOOD TO WALK AROUND IN AT NIGHT. This is an inexcusable error.
3. The advice about avoiding bus lines and relying on cabs in questionable neighborhoods is useless. Cabs won't go to questionable neighborhoods. On the other hand, buses in questionable areas are often safer- there are often people around bus stops, and the bus drivers keep something of an eye on things.
Those are the examples I had to point out as a warning to people from outside DC who might be tempted to rely on this guide. There are other issues with the guide- a bit of snarkiness, and I'm not sure I'd consider Rock Creek Park, a nice city park, to be more of a must see than the Lincoln Memorial. (If you need your green space, there are much better ways to get it, such as Great Falls or a short drive towards the mountains.)
Also, sights considered, for travel purposes, part of the DC area, such as Annapolis or Manassas, are ignored.
Bottom line: Usually I love Rough Guides when traveling. This one isn't up to the standards to the rest of the series.