I read thousands of posts like this on various forums when I was considering getting evaluated. Everyone seems to have vastly different experiences. For mine I saw a psychologist for two hours at a time, and we did each of these:
1) Went over my history starting as early as I could remember through to present day.
2) An IQ test.
3) Some additional tests of math (I am terrible at math), vocabulary, writing, and auditory processing. Then we talked for awhile about some of my problems and how I felt I fit with having Asperger's.
4) A massive personality test.

Once all that was completed he talked to my mother on the phone. He wrote his report and we went over the draft version. He said that a year ago I would have been diagnosed with Asperger's, but he isn't sure I quite meet the new requirements for ASD. He's not sure if I have enough examples of restricted interests or repetitive movements and want's me to follow up with a psychiatrist for further testing. We may have had a communication problem as we never actually discussed my interests and he seemed to ignore the repetitive movements I do (leg bouncing) and focused more on how I rub my hands while talking. My wife and I actually saw him over the weekend and he is fairly convinced I have an ASD but isn't certain enough to put it on paper.

For me the experience wasn't bad and it gave my therapist tons of more information about me that she wouldn't have had otherwise.