I think she is by far the best singer in the world and the greatest female singer ever. She has covered a wide variety of music, showtunes, classical and pop and is perfect on all. She is also a great actress director and producer and a great role model for people.
I love singing her part in "Tell Him", a duet with Celine Dion. I also enjoy singing with her and Kim Carnes in "Make No Mistake, He's Mine". I don't know much of her music, but she does have a beautiful voice. I am going through a period of "Enlightenment" right now where I am listening to all the music I can. I am digging into the musical past looking for new people to listen to because I don't like much of what's coming out now. Barbra Streisand is definitely on my list of people that I want to learn more about and explore the music of.
I advise you to start with 'The Essential collection' and then decide to explore because there is alot of stuff by her. She is infact the biggest selling female artist ever, she has sold more than the Beatles. She has infact recorded two Lennon tracks, 'Mother' and 'Love' not quite as good as the originals but helps to expose the beauty of them in a new way.