Oh boy... that's an issue I've wrestled with several times. I can't tell you how many times I've started to write a new thread on the subject of pocket squares, only to delete it and tell myself, "You know darn well what the answer is going to be. Some will say yea, some will say nay, some will show photos of pocket squares, some will say it's too this or that." So without even opening that particular can of worms, I've just decided I'll wear one if I feel like it, and don't if I don't!

I do think a pocket square can add a bit of finesse to an outfit, especially by varying the colour/pattern or method of folding it (I know of at least 4 common methods). It's one of those fine details that should be a finishing touch. Give it a try, and see how you like it!
I agree... it is one of those flourishes that is hard to put into words. Some days I just take the fancy and shove one in and other days it is just too much faff so it is left at home.