I absolutely adore this name, it's one of my favourites. When you hear it pronounced the Italian way - I haven't heard the Russian way - it is a strong and assertive name, that also has a rather romantic sound.
Coming from an Italian background myself, Violetta sounds much better than the English name of "Violet", which is very passive and weak.
My mother's name is Violetta (we are Russian), she is coldly beautiful woman and very tough, burst-type, I might add. There is nothing sweet or flower-ish about her. Therefor, for me this is very strong and powerful name.
I like this name better than Violet, because it's not so close to the word violent, and the flowers and Italian language are very beautiful, of course. It also sounds like 'via letter', which is amusing.