It's an old book (1996) with a bit of a dramatic title, but the guy is all science:
Excitotoxins: The Taste That Kills by Russell L. Blaylock
The section on the aspartame trials is very educational.
It bypasses the blood brain barrier (not something I'm a fan of) and breaks down chemically with heat. Very unstable. Toss in the more recent studies that have shown artificial sweeteners tend to make you crave sugars even more, and I don't get the point of using it. I prefer to use the real stuff and train my taste buds so they don't need nearly as much.