I've heard others say it helps with mood, energy, depression, etc. and if that's the case for some people then great. I don't notice it myself but that's just me. Not everyone has the same body chemistry.
Did you try higher dose. You need to take 0.35g/kg body weight for effects on brain, atleast thats the doses that are usually used in the studies. I believe your body will distribute it to your muscles before any goes to the brain, so you need to take a dose that will saturate your muscles and then have extra left over. I take 25grams whereas the usually reccomend daily dose is 5grams
I did a week trial at 20 or 25g/day once. This was after being on the standard weightlifter's 5g/day for a while so muscles should have been fairly saturated. Didn't notice any effect. 0.35g/kg dose seems like way more than our bodies would have ever had even in a prehistoric hunter's diet. For me that would be 30g/day.