Note, though, that while it uses Instagram's API, it's neither endorsed by Instagram nor designed to support posting of photos and videos to Instagram.
Nevertheless, as it stands, Primary is already packed with features, even more so now at version 3.0.
Compatible with iPhone, iPod touch, and iPad running iOS 8.0 or later, Primary 3.0 includes support for Background App Refresh (so that your feed is always refreshed) and 1Password integration (so that you need not enter your password manually).
Primary 3.0 also boasts native resolution support for iPhone 6 and 6 Plus the better to see Instagram photos and videos in their full glory.
Primary for Instagram
Primary 3.0 also includes the following enhancements:
App badge: see how many new posts are waiting for you
Auto-theme change: theme updates based on screen brightness
Faster photo hiding: swipe right-to-left to hide a post; keep swiping to hide the person
Shake to undo: accidentally hid something? Just shake to bring it back
More sharing options: long-press to share
Fullscreen optional: you can now choose to show the status bar while you browse
Show real names: choose to view people's full names rather than usernames
Unread comments improvements: better syncing, Unread comments list, indicator in the thumbnail view, and an option to remove the indicator
Text filter improvements: you can now choose to filter based on the text of the caption, not just tags
Key commands for iPad: +12345 to jump through sections, up/down to scroll, +F to toggle filtering, +R to refresh
Thumbnail scrolling: automatically loads more in the thumbnail sidebar