New logo is okay, but they must be hurting for sales if they needed such a drastic change, specially for the can and not just the logo.
I love Mountain Dew, but Coca Cola blows away Pepsi in terms of cola products. But I do like Vault and the red-flavor Vault too, sometimes I feel like Vault, sometimes I feel like Mountain Dew. Main difference is just the amount of carbonation - MD has very low carbonation and tastes sweeter in comparison to Vault, which has a lot of carbonation and doesn't taste as syrupy, though still sweet.
To be noted though, I NEVER feel like drinking a Pepsi, and never buy it either. I'm hardcore for Coke, and yes... I guarantee in a blind taste test, I will distinctly identify Pepsi as the flavor I do not like, as I can taste a noticeable difference.
And Coke made with sugar, while definitely better, is not worth of cost. Now when they start selling Kosher 2-liters with sugar (if they sell them around here), then I will buy them up because I think they are the same cost or similar. But when it's like 1.75/12oz bottle, hell no.