I'm of the belief that note taking does 2 things for you.

First, it gives an idea of what the player is doing next time you face them. I take a lot of notes of different players at FTP, especially if there is a lot of action at the table. I've run into many players that I have notes on. It's helped me more than once make a call with a weak hand because that player has bluffed at pots with nothing in the past.

Second, it forces you to pay attention to what is going on at the table. If you watch your table, even when not in the hand, you will pick up more useful information than you think. Most sites allow you to see the showdown cards of all the players that went to a showdown if you were dealt into the hand. I've used that information to beat players multiple times. I've found, through experience, that if you do those two things, along with a few others, you will make money playing poker in the long run.