Warning: The food here will spoil you for "normal" barbecue. This is traditional Texas barbecue at its very best. The brisket is always trimmed completely--no fat or gristle. The sausage is sublime and not greasy. Any meat that's barbecued/smoked is perfect. I've been eating barbecue weekly since early childhood, and this is just the best there is.
The atmosphere is family-friendly and casual. The decor is rustic but comfortable. Service is very attentive. You can eat "family style," where you're brought platters and platters of food until you all say "enough!" Or you can order a platter, which I guarantee will require a doggy bag or a huge appetite.
The view is lovely--a shady, narrow arm of Lake Austin that is really the entrance to Bull Creek. You can drive your boat up and dock it, or you can park your car in the lot. There is no bus service to this upscale part of town.
It's not traditional to think of barbecue as an "upscale" dining experience, but this is the creme de la creme of barbecue. It's still pretty reasonably priced--you could spend more than $10 if you had alcoholic beverages or if you did the "family-style" thing, which is about $14 per person.
If you want to eat after 7pm and don't want to wait a half hour to an hour on the shady outdoor pier drinking margaritas or iced tea (which is actually a pleasant way to spend an early evening in summer), make reservations. If you want to eat before 7pm, don't worry about reservations.
There's a newer County Line on the Hill overlooking a vast valley, just off Bee Caves Road, but it's not quite as nice a setting, in my opinion, though it has great "forever" views.