I am torn over Old Sugar. I have been there many times and brought many people there. Unfortunately, I feel like every experience never lives up to my first experience there. It is likely the failure of memory, so here is my breakdown.
Atmosphere - Awesome. It feels like you snuck into the middle of a distillery and someone is serving you drinks there. One night a guy that sounded like Tom Waits was singing and I thought I had died and gone to heaven (Tom Wait's version of heaven, of course).
Drinks - Strong. The one thing that bums me out about Old Sugar is that I feel they could do so much more. I mean, they make their own liquor, so you would think they have some fancy cocktails. They aren't terribly fancy, or fantastically executed. And they only have 1-2 rotating cocktails, otherwise it is the same ol' thang.
Price - Affordable. Usually $6-$7 a cocktail
As others have noted, it closes early (10 pm) so you should get there early. It is a good standard place with some classy novelty.