Olbia is a ferry port, so you can easily get in by ferry/cruise ship.
Beware the way locals drive: racing along the narrow and bendy roads in the hills.
Ristorante Gallura is certainly one of the best restaurants in Italy; it may also rank among the great restaurants of the world. Rita Denza, the chef, has been there since 1945, and she has an absolute mastery of the kitchen.
You may encounter poor road conditions, with potholes and open grids. Also the skill of some drivers leaves something to be desired.