Gluing is fantastic if you write in terms of chapters, or bits of discrete ideas inside chapters. It allows for focus, as well as easy rearrangement of subsections of writing.
The only things I miss in Ulysses are two features in Sublime Text: side-by-side split view of a document, and a miniaturized view of the entire document letting you see where you are inside it.
Those aren’t deal-breakers, but I’d love to see one or both in Ulysses.