The dealership is very nice if you have warranty. They always treated me well (when you're out of warranty they're expensive). It's BMW of Austin. If you're out of warranty I'd recommend one of the independent BMW mechanics. Personally I've used Black Forest Werkshop on Buell and German Auto Center on 183 and both I found to be good guys.
'07 335i E90 | Cobb Stage I
'03 Porsche Boxster
'07 Alfa Romeo GT 2.0 (sold) // '06 325i E90 (stolen) // '99 Alfa Romeo 156 (sold)