We went to Oga's twice on our trip last week. Really enjoyed it both times. Got the 2 mugs on our first visit. Ordered a Fuzzy Tauntaun on our second just to see what it was all about and we loved it.
A couple of things...not everyone has to order a drink. Both times, our daughter didn't get anything and the 2nd time we just split a drink. We also saw more than few people get placed next to us and they looked around, took photos, and left. So there are plenty of people making reservations just to get inside and check the place out.
Would totally recommend going, we had a great time. Also never felt rushed, but they do crowd you in. And the first server encouraged us to take our coasters, which was nice (we were taking them anyway).