Read this post (and comment following) then answer the question!
It strikes me that proponents of Sola Scriptura may too readily overlook all the ways in which even the most Scriptural of Christians do not actually live by "Scripture alone" (using commentaries, approaching Scripture with the guide and guardianship of the creeds, endorsing preaching as means of bringing understanding of the bare text to the congregation).
But just before we strike Sola Scriptura down, let's acknowledge the Reformers were no fools. There was a reason for their holding up Scripture as the ultimate determinant of the message of salvation. Something had gone terribly wrong in the reading of Scripture in and by the church towards the end of what we now see as the medieval age. A church promoting indulgences as a means of raising finances to build an edifice is not a church reading Scripture with the grain of Scripture. Nor is it a church understanding, let alone fulfilling its responsibility as guardian of Scripture.
Part of the point of the post linked to above, as I reflect on it, is that just as there are different ways to understand Sola Scriptura so there are different ways to understand "not Sola Scriptura."
One of those ways, in Western Christianity at least, goes something like this (at least in the minds of Protestants!): Scripture and Tradition inform the Christian mind; with Tradition being the accumulated knowledge of the church as it has discerned the mind of Christ through many centuries; so "not Sola Scriptura" means Scripture PLUS Tradition, two streams of knowledge and revelation from God, the key to holding both together being the church. Cue arguments for a formal Magisterium or an informal magisterium via theological faculties; for acknowledging "tradition" but not "Tradition"; for Sola Scripturists being extremely dubious about Tradition (if not tradition) because the former has permitted strange (= unscriptural) doctrines like the Assumption of Mary.
But another way, heralded in the post, is that Scripture is a text in which there are treasures of spiritual knowledge, indeed, better, one treasure of knowledge, Jesus Christ, and the shortfall to "Sola Scriptura" is that it offers a limited understanding of that treasure whereas the church's gift and task is to corporately read Scripture (i.e. gathering all readings together, past as well as present) so that the full knowledge of Jesus Christ, from every page of Scripture is brought forth into the light.
I remain somewhat Protestant about the first kind of "not Sola Scriptura" and I am drawn to the Orthodox direction by the second kind of "not Sola Scriptura."