Wallpapers HD is possibly the best of this kind of app I've seen in a while. The interface is straightforward with a quick menu at the top of your screen that allows you to see images that are the most recent, most popular, and even just provide you with a random choice. You can start browsing right away.
Browsing is simple: by using the arrows at the bottom of the screen you can view images in blocks of four or one at a time. You will notice a button between the arrows; by tapping this you can search the images by category. Once you've chosen the category, just view the images until you find the one right for you.
Select Your Image and Away You Go
Once your image is selected, Wallpapers HD will ask you to select the size. You have two options: "fitted" or "full." Selecting the "fitted" option does just that: it downloads the photo so it fits perfectly on your device's Home or Lock screen.
Selecting the "full" option downloads the image in its original format and allows you to move and resize the image to display exactly how you want it.
The photo quality is well above par in all cases. There isn't one instant where a photo didn't look pristine. The download time for the image was immediate, and within seconds I had my new wallpaper and was already looking at more.
If you're having trouble getting the right wallpaper, or enjoy changing the look of your iPhone or iPad frequently, you should definitely try Wallpapers HD. It's free, it's fun, and you will definitely find exactly what you're looking for.