There are massive differences, since Sedes still believe in almost all Catholic doctrine. Outside of the legitimacy of the current pope, all the differences between the Catholic and Orthodox stand (essence/energy distinction, created grace, filioque, role of councils, papal supremacy, hesychasm, etc. etc.).
Speaking as an Orthodox Christian, the general opinion that I've heard on Sedes is that they haven't gone far enough, more or less. They agree with the Orthodox position on the Papacy to a degree but are unwilling to admit that the Orthodox Church has things right.