If you are a visual learner, the value of note taking on screen can be really useful however i agree with
@dannystanks that having a small notepad is useful for an instant note especially during a game or when multi tabling.
I will often make a note on a player if they make an interesting play whether that be a loose call or a speculative play and it definitely helps, especially so if you are playing against them regularly for example our
freerolls and leagues.
We have a lot of very good poker players here at CC so its worth noting down trends, patterns, bet sizing, LAG and TAG players as well as the NITS.