Are you considering getting roll up window shades? They can be great if you have the money to purchase them. the great thing with Roll up shades is that they have a mechanism that can be pulled to release the shade so you do not actually have to pull a string. this is on some models.
Others actually have a mechanism that can be pinned down to an anchor, and can be pulled in one direction or another to the desired height. These also can at times come off of the roller if they are not made well, or if there is too much play in the actual roller. Make sure that whoever you purchase your blinds or shades from that you check to see that they are in working order.
A lot of people do not double check their blinds or shades, and this can leave the person that is installing them with room for error, or leaving them if there are defects. make sure to always check them whatever you do, and this will relieve a lot of possible future issues.