The Word is both.
Revelation 10.10
Then I took the little book out of the angel’s hand and ate it, and it was as sweet as honey in my mouth. But when I had eaten it, my stomach became bitter.
John’s experience of eating the Book recalls the work of Jesus. While it was sweet for Jesus to do the will of God, it was bitter as well, because of His suffering. And this should give counsel to all who feed on the Word of God.
There is much in Scripture to delight the soul, to give us hope, joy, peace, and good counsel, and to make us more like Jesus. It is sweet to feed on these words and to be strengthened by them. But they are bitter as well, promising trials, tribulations, disappointments, and setbacks, and reminding us that the life of faith is a difficult road.
The Word is sweet because it holds out precious and very great promises; it is bitter because it exposes and indicts sin, rebellion, and wickedness.
It is sweet because it shows us Jesus, but bitter because it promises we must share in His sufferings.
It is sweet in revealing the coming of the Kingdom, but bitter in reminding us that we must enter that Kingdom through tribulations.
It is sweet in reporting the steadfast love and faithfulness of God, but bitter in reminding us of His discipline.
It is sweet because it is so very clear and easy to understand, yet bitter because so many of its mysteries lie beyond our reach.
It is sweet in leading us into life in Christ, but bitter in calling us to die to ourselves.
It is sweet because it draws us into a life of rest, but bitter because it calls us to proclaim the Kingdom and be witnesses for Christ in a hostile world.
Thus we must take the bitter with the sweet, and be taught and edified by all the counsel of God in His Word.