QuiltCut also makes a
ruler with guides for cutting strips in various widths, and I've been very happy with it. When researching my options, I found it interesting that there were a number of comments in the reviews about the QuiltCut having aspects that made people prefer it over other brands - one was that the slots were a bit longer than another brand.
That said, you don't need one of these fancier rulers to cut strips, squares and rectangles quickly with a rotary cutter. The basics are simply a mat, a rotary cutter and a clear ruler with a good lines. A 6" x 24" ruler will let you do a wide variety of cutting. If you do a google search for rotary cutting videos, you can find lots of videos that will show you how it all works and give you some good tips. Important safety tip:
*always* retract the cutting blade when you aren't holding the cutter and make sure your other hand is well/safely placed before you start cutting.