I have talked to a few people about Habana over the last few days, and two told me about their experiences of receiving bad service there. I've also read several comments on city search websites that include user reviews of restaurants, and many of the comments on Habana told similar stories of negative customer service experiences.
It was not busy when I ate there, and my friend and I had simple orders. There was not much room for error. Our server wasn't all that talkative, but she was attentive enough to make sure we had drink refills. She deserved her $3 tip.
However, I felt inclined to mention the restaurant's reputation for bad service. It's a laid-back place, but instead of translating into a chill island-themed feel, it's coming through in mistreatment of those paying the bill. This is Austin, not Europe. Servers need to be honest and timely, and when someone asks to speak to a manager, they should always speak to a manager.
My experience warranted four stars, but I'd say based on what I've heard, it's not always the typical Habana experience. You are now warned.