Well, she wasn't exactly Ella Fitzgerald, but for the kind of disposable pop Blondie aimed to be she had the perfect look and a girlie voice to go with it. I actually liked her voice better in her later years, when she had lost highs, but finally gained some timbre. This sounds Chrissie Hyndish in my ears, who is not a great singer herself, but makes her voice work for the songs she sings.