I've just been testing Manuscripts, and i love the simplicity of the layout, the features, and the look.
However i often have trouble getting rid of the first item in a numbered list using the delete key. I like the gutter hidden, so although that seems to work to get rid of stubborn first items, i'd rather not use it.
The better alternative is to select the list-that-won't-go-away in the binder (left) and delete that. Still, it would be nice to have the delete key working.
Reading about the frustrations people have had with various features of Ms is disappointing, as it echoes my limited experience - even though Ms is beautiful. I like it, though, so will continue using it. If it becomes too frustrating i'll stop, otherwise if the irritations are relatively minor i'll keep going.
In any case, i appreciate the opportunity of being able to use it!