Type in an Instagram username, and instantly download their image feed. It's not often I can describe 100% of an application's functionality in a single sentence, but when it comes to free utility 4K Stogram, I just did. See Group test: what's the best compact camera?
4K Stogram doesn't require you to log in to Instagram; it doesn't have a preferences dialog, and offers no way to Like photos or comment on them. It can't be used to view or download tag feeds. It doesn't even let you pick a location for the images it downloads, instead making the decision for you. In other words, it is an exercise in focus, and is as bare-bones as it could possibly be. Take a look at Visit Nikon Coolpix S9100 too.
If you are looking for a more complete Instagram client for Windows, you might want to check out free Pokki app Instagrille, which lets you read and reply to comments, Like photos, and more. But if all you need is to download Instagram photos in bulk, that's exactly what 4K Stogram does.
4K Stogram takes an Instagram username and downloads their photo feed in one fell swoop.