I love the fullscreen mode of Sublime Text and use it completely to the exclusion of the normal windowed mode.
When the window is large (as it is in fullscreen), the minimap shows more and more whitespace (not whitespace characters, just empty space on the screen) to the right of the text, thus making the actual text part of the minimap smaller and smaller.
It would be nice to have the option of making the minimap consider only the width of the text. I realize this breaks the 1-1 correspondence between the screen and the minimap, so perhaps it is undesirable or impossible, but the fact is that as the window gets larger, the minimap gets less useful. To me at least.