I lived in Houston for a few years, and I tried a lot of BBQ over there. Holy Smoke is definitely good. I liked the ambient, the decoration and the service wasn't bad. The washrooms were nice and exceptionaly clean.
The BBQ sandwich was good, the small one I think is very small. Next time I'll go for the large which has twice the meat for only 3 bucks more. My only complaint at this point is the meat temperature: It wasn't fridge cold, but it also wasn't even warm. I'm not sure if is healthy to keep and serve food at that temperature.
The sauces are very good... you'll be tempted to try them all. Corn bread was nice but probably too sweet (and a tad expensive). In all, it was a nice experience and will go again for sure as long as the "room temperature" meat doesn't kill me.
One more thing, you can skip the Pecan Tart. Not even close to a southern Pecan Pie and twice as expensive.