Yes, the first few hours were a problem, but I went through the AMA site yesterday and it took me about 20 min or so including a careful read of all the material, I could have done it MUCH quicker if I just clicked through to the questions.
They probably should have done a better job planning for the initial peak with their hosting company, but as others have said, this is not an uncommon problem and they certainly would not want to size their service on an ongoing basis for that short duration initial peak as it would drive costs way up. I also suspect that the AMA site got slammed harder than the other sites due to the high concentration of AMA members all getting the e-mail simultaneously and jumping right over to site. Perhaps another technique that could have been used was for the AMA to have phased out the initial announcement e-mail in chunks over a 24 hour period (this is another tactic often used to minimize impact when you expect high volumes at the launch of anew site).
All in all though, I think that the AMA did a great job coaching the FAA into making this more of a training exercise and less of a true technical knowledge test. My understanding is that this started out being a very lengthy and technical "test" and the AMA (and I am sure others) helped steer the FAA towards something much more approachable. Assuming that is true, then credit where credit is due.