Cecilia Bartoli has been praised enough, there is hardly more to add.
I want to draw your attention to the cast of this excellent performance. Raul Gimenez is superb as prince, with a wonderfull soft, flexible, tender voice thankfully very unlike the tenors that are just powerful, but who lack a feeling for the music they sing. I think he is one of the best Rossini tenors around.
Alessandro Corbelli, as Dandini, is a very good baritone. He has a powerful, yet soft and flexible voice and is good at acting as well as singing.
The two daughters have maybe not the experienced voices of the older members of the cast, but their singing is good, and the faces they pull during the performance are immensly funny.
The opera gets better with every time you watch it, and as it is also filmed very well, and has a good quality of sound, and nice old-fashioned costumes (not like these German productions with modern outfits) it is definitely a must buy!