I know the 0 cal thing sounds good, but there are a lot of negative effects as well. Not saying I will never drink it again, but I am not going to be drinking 2 cans for breakfast thinking it is a replacement for coffee and then having more throughout the day.
What are the negative effects?
I read somewhere and believe it's true from experience that artificial sweeteners do something that triggers hunger pangs. 
Ive "heard" it can affect short term memory loss. Lots of articles going into the issue with aspartame. Who knows for sure.
big_slacker - What are the negative effects?
it's bad for ya.
for real though, water retention and a few other things.
You are likely fine with 1-2 a day. I was drinking more than that some days.
You can googe some of the other negative effects. Some are still up for debate, but others most people agree on.
I don't really drink diet soda, but I do 1-2 monsters (lo carb version) a day. I haven't noticed anything horrible which was why I was curious. Didn't want to find out it had been eating my brain or something.
well moderation is obviously the key. I love diet pop like I love beer, but you can't have that shit every day.
Day 4 no diet pop
Day 27 no alcohol
What you need to ditch is John Cena.
reagan123 - Ive "heard" it can affect short term memory loss. Lots of articles going into the issue with aspartame. Who knows for sure.
I heard it causes...
Ah shit, I forgot what I was gonna say.
Oh I remember. I heard it causes....
CANCER!!!!! like everything else in this world. 
Diet sodas spike your insulin even if there's no sugar in them.
Aspartame
ASPARTAME