I successfully made it 6 months without drinking soda. It actually wasn't bad. I don't drink a lot anyway (maybe 1 at lunch 2 times a week and then 1 on the weekend with a meal), so it wasn't a struggle. What was difficult was ordering at restaurants (basically fast food). There aren't a whole lot of drink choices if you don't want something chocked full of sugar. I tried to stick to iced tea if they had it.
The worst part about the challenge was at my birthday party. There was a ton of soda to drink and I couldn't have any of it. That's what they made wine for though, right?