IMAGX - Most Beautiful HD Images 1.8 for iPhone - Download
More than 100,000 wallpapers for your iPhone
With the sole requirement of having some sort of Internet connection (whether it's WiFi or 3G/4G), this app will let you download as many images as you want from any of 20+ different categories, all of them updated each day with the best HD content: 3D, abstract, animals, animation, cars, city, fantasy, flowers, food, games, girls, holidays, macro, guys, movies, music, nature, space, sports, textures, TV shows, vector images, and more.
Check out any category of interest, click on the picture you like best, and select one of the save options (save it to your device, upload it to your iCloud account, or email it, which could prove quite useful if, for instance, you want to set the image as a wallpaper on your personal computer or include it in a web project).
Now there's no reason not to keep your iPhone looking fine given that you've got all these thousands of high-quality images available.