Templates save you money: If you use a royalty_free template, it likely costs less than hiring someone to create a custom graphics package for you. You could easily spend hundreds (or possibly thousands) of pounds on a custom motion graphics opening, for example, whereas you can frequently purchase a royalty_free template for under £200. Of course, the royalty_free template isn't as unique as a totally custom template, but it definitely costs less, and you could always customize the royalty_free template to make it more unique for you.
The other design factor aside from the text is the imagery that you can use. Many of the newsletter templates will come equipped with basic clip art or graphics. Others will include areas where you can paste in your own graphs, photographs, or other graphic items that help round out the information. It's important to remember that the first thing that people often look at, even before the headlines, are the images, so make sure that they are strong ones that are eye_catching. Color newsletters also tend to be more appealing than those in black and white, though they can cost a bit more to print.