Hey, I'm one of the people who posted about a bad experience in Atlanta on another thread. The airport itself is clean and even had some nice art that my kids enjoyed looking at (blown glass and such). The signage is good and there was a decent selection in the food court. There were plenty of clean restrooms as well - very nice, in fact. However, we (and the other 2000 people in line with us) were treated rudely by security, and after we'd been up nearly 24 hours, we didn't really appreciate it very much. (and I'm not joking about 2000 people. There were nearly 200 on our plane and within moments of our landing, large planes from Norway, Denmark, Greece, and somepplace else had landed and we were all in line together at customs and immigration and then security. Hello? If you KNOW that many people are landing at once, get some more screeners on the job - it was 4:30 in the afternoon there, not exactly a weird time to have people working. Sheesh!)
However, as everyone has said the airport is HUGE, one of the largest in the world I think, and so it takes a LONG time to get from point A to point B. You will need the whole two hours.