Yup. Both with having side-effects and with digging through long list of ingredients to make sure that something I’m going to eat doesn’t have Aspartame in it. (A good indicator is if it warns Phenylketonurics not to eat this.)
My side effects varied. From food and sodas, I get nasty, nasty headaches. I really think it’s had a negative effect on my memory, too. For a while I tried to do the Slim Fast thing, and the powdered mix gave me the most bizarre sensations–like I was kind of drunk but with serious caffeine buzz. My insides just quaked and I could feel my blood rushing through my veins with each pump of my heart. After the second “meal”, I stopped. (Note, though, that the pre-mixed, canned stuff doesn’t have Aspartame, just the powdered mix.) I even get headaches now from breath mints or chewing gum that has Aspartame in it.
My suggestion for you (if you have to beware the stuff) is to avoid anything that has the word “lite” in it. Nine times out of ten, it’ll have NutraSweet in it. You’ll have to learn how to diet without using those products. (Which sucks rocks if you want my opinion, but, what else can you do??)