The company should be able to provide you with more than one type of brick style for your wallpaper so that you can be sure you're getting the kind you want. Sometimes you will find that you just don't like any of the wallpapers, and that is fine since you can look for other companies to help. If you did have something in mind and have the graphics for it, you can get this printed for you also.
If you do decide to get custom wallpaper printed for you with a brick theme, you need to make sure that the images you use are very well made. It is best to go with something that is a very high resolution and in the file type the company has no problem working with. Before you use something for wallpaper it should also be able to line up in the squares that you will be working with. If it doesn't line up and create a seamless barrier, you may end up not being able to use it since you will be able to tell where the image ends and it will be distracting.