Overall Atlanta is a good airport UNLESS you are flying in international and plan to over night in Atlanta.
On February 9th 2013, we flew into ATL (Hartsfield–Jackson Atlanta International Airport) fr om St. Lucia, with an overnight stay. We flew into concourse E and had an extremely long walk to get to customs (we walked past customs for connecting flights and kept going and going). This however, was not the worst part of the experience.
The worst part was after we cleared customs and immigration we had to wait take an airport shuttle through town, past our hotel, to get to the airport hotel shuttle center, as the hotels are not allowed to pick up at the new terminal. This trek added about an hour to our trip vs the old process wh ere you rechecked your bags, went through TSA, and took the underground train.
Very large airport. If you don't take advantage of the underground train system, be prepared to do a LOT of walking! Airport is very organized and you get through security check very quickly. Every time I go through ATL I get selected for additional search. But it's always pleasant!