One of my favorites in Vegas, no question.
The patio (with ample misters for hot weather) and the rotating tap list are the stars. My wife and I don't like smoky video-poker bars, so the patio is a perfect solution relative to, say, a place like Aces & Ales, where the beer list is awesome but the smell and the haze can be brutal.
Service is awesome, with a staff that's hyper-professional and friendly even during rush periods. Their bar manager Rose is particularly efficient and friendly, and makes excellent and specific beer recommendations.
Warning: they don't have a kitchen. But there are a number of really great food options nearby, including at the Container Park just a block away.