I assume it's good since it's pretty much the top choice for what it does. You can either set an image as your wallpaper, favorite it, or save it. I'm trying to figure out where it's saved at. It says something along the lines of SD ..insert text here.. Backgrounds. I see nothing of the sort my Eris, nor do I have any clue on how to access this location. Saved wallpapers are not in the albums. Is there a way to search on the phone, or search through the card via desktop? I just bought the phone, so I'm still tinkering. Quite a learning curve changing from a Blackberry.
To browse the SD card from your PC, just hook it up with the data cable, pull down your notification window and select Mount SD card. The phone's SD card will then show up as a hard drive under your "my computer" just like a "thumb drive" would.
You can browse, copy, delete, drag and drop what ever you like from/to your PC, transfer music, ringtones etc.
If you want to browse the contents of the SD card from the phone itself, install a "file manager" like LInda File Manager, available from the Android Market.