I am not a big soda drinker. I have my bouts with Diet Coke, but can't usually stand the way that soda's sugar coats your mouth and makes you feel gritty on the inside.
Diet Dr. Pepper, on the other hand, is a blessing from the refreshment gods. And yes, it does taste just like regular Dr. Pepper.
To continue the earlier theme of self-education, I direct my audience to Wikipedia. In particular, the Wikipedia entry on Dr. Pepper. What is this wiki-thing? A collaborative encyclopedia where anyone can edit any entry. Every day there's a daily article, so if you check it out, you'll learn something totally new every day.