Of course the most difficult thing on the violin is always intonation. The second one is rhythm. If you play in tune, in time with a good sound that's already high level. Those three are the main things.
Ruggiero RicciSo, first you have to be able to play with a metronome. Then you take your freedom. If you play in an orchestra, you got to watch the conductor, he is like a metronome, but it is more difficult because he can change rhythms.
Ruggiero RicciA good interpreter can take a piece of bad music and make it sound pretty decent, while a bad interpreter can take good music and make it sound cheap. I can tell that some people have a bad taste, and unlike on the piano, they smear around a lot, that is bad taste.
Ruggiero Ricci