Every violinist has a different style, so it's important to be able to recognise their styles. You don't have to like everyone's style but you have to know these styles.
Ruggiero RicciOf 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 Ricci