I had some cognitive testing when I was first diagnosed withe epilepsy as a child. I remember some of the tests/games, and that I had a college level vocabulary.
In 2006 I saw a neuropsychologist in Boston. She was awesome. With her and a graduate assistant I took two days of testing (probably less than 6 or 8 hours total). It was a bunch of tests or mind games. It wore me out a bit, but I thought it was fun. Mostly I liked the idea that someone might for once acknowledge that there might be something wrong with my memory and cognition. She met with me twice to discuss the results. The "good" parts were that I had a problems with working memory (like doing math problems in your head), I was very slow even with things I was good at, and I was terrible at math compared to other things. She said that I did not have memory problems, which I disagreed with strongly. The difference seemed to be that in her opinion I had problems "encoding" information rather than "remembering" or recalling it. That may or may not be right, but it seems to me that if you can't remember something you have a problem with "memory". The "bad" part was that she told me I am very smart (according to what measure I don't know), but that made me feel bad because I felt like I had little to show for it. We also discussed some of the results from the standardized testing I had taken (ACT, SAT, GRE), as well as my college transcripts.
For the most part we stuck with the results of the tests she did, but she took quite a while with me. One thing I remember that was very helpful was that she said she was impressed that I had persevered with my education in spite of my difficulties (7 1/2 years of college at that point - I was in grad school). I had always been so frustrated because I felt that I was smart enough, but just couldn't get the sort of grades I wanted or needed. I studied for some stuff more that necessary and got "C"s, then did the minimum on other things and got "A"s. Overall my GPA was mediocre to ok, or even good, but not good enough. So, I felt for a long time like I was little better than a failure. Since high school, academically I had often felt like something of a delinquent. She was the first person to see that I tried hard (and I did), and to acknowledge that I had some significant challenges that others at my level did not.
She also suggested that I see a psychiatrist in the neurology department to discuss minor depression issues. I saw him once. He prescribed me some anti-depressants, but I didn't fill the prescription. At the time I couldn't see what the good of taking another pill would do, especially if my meds were the worst of the problem (as I thought). Perhaps I should have tried it, but at least I got to talk to someone about it and have the opportunity.
I saw the neuropsychologist again a couple years later. She did some of the tests again. I did a little worse on some of them (I was on a lot more medication), but for the most part was the same. I felt better that I had some proof (at least in my mind) that the new meds were causing cognitive issues.
Overall, it was not life changing. She did make some suggestion as far as academic "accommodations", which never came to much and I didn't like using them. I had already figured out most of the life strategies I discussed later with one of her graduate assistants. It did change my perspective on my pursuits. Academically I decided that I was just not going to waste time on things that I knew from long experience, and from the test results I wasn't good at. A sincere try is one thing, banging your head against the wall is another. I decided to focus more on my strengths. I had spent way too much time on my weaknesses up until that point.
For the most part I was very glad for the experience because it did give me some objective measure of what was wrong with me cognitively, and it was about the only time anyone ever acknowledged my deficits, rather than telling me I was imagining things or was just lazy or something. It was a positive experience.