Roman shades are very popular now a days. One advice when selecting your fabric, make sure, to use plain or vertical stripes cottons. Cottons are preferable, they are an excellent fiber for roman shades. Avoid print with horizontal repeats, such as floral or geometric prints, plaids, or any print with horizontal repeat that was printed, and the print does not match the grain of the fabric. In this case the roman shades will appear crooked when hung, and which will not look proper! Other fibers can be used such as polyester blends and some silks. It is always a good idea to ask a window covering professional if you are in doubt!
See the picture below, the print is off by approximately one inch.