I'm going to start a list of things Sketch needs to get right. I call them basic because that's what I'm used to on Adobe products and Sketch is a direct competitor (in many ways) to Adobe:
The ability to lock rulers from moving.
When creating grids there's no option to add margins.
It's difficult to see where you're placing a guide because the numbers on the ruler get in the way.
A 'Save as' function.
Clear all guides in one click. It's annoying when you have to create a grid for a website and because the rulers shifted you end up placing guides in the wrong place then you have to drag each one off individually.