From the doctrinal point of view, is Opus Dei 'traditionalist' or 'traditional,' and how does this accord with Vatican II?

'Traditionalism' is an aberration that takes different forms, all based on a mistaken concept of 'Tradition.' The genuine meaning of 'Tradition' is important for the Church because it is inseparable from Holy Scripture.

The Church possesses a splendid history composed of spiritual treasures in the saints. Their lives illuminate the past twenty centuries and they illuminate our time as well. The Church has generated an incomparable culture in art, science, and literature, along with schools and works of charity. At the same time, the Church's history is alive today in the hearts of her members who continue to be guided by Christ--the same today, yesterday, and forever.

The Second Vatican Council spoke about all this; in the conciliar texts one can find many of the ideas our Founder already began to preach in the 1930s. All of the councils form a magisterial unity without any contradictions. So I would say that Opus Dei finds its 'doctrinal homeland' in Vatican II, composed both of what is traditional and what is new.