Facebook (who acquired Instagram a few years ago) have just released a new beta version of Instagram. This is not to be confused with the Instagram BETA app that has been in the Windows Phone store for almost 2 years, that version doesn't even have direct messaging feature.
There is a very complete Instagram app in the Windows Phone store developed by Rudy Huyn, it is called 6tag and is the best alternative to the official Instagram app. 6tag even allows you to save Instagram photos to your gallery where the official Instagram app (including Android and iOS versions) does not. that's why users usually take screenshots.
This new Instagram app is a complete port of the iOS version with a lot of new features (compared to the Instagram BETA), features like direct message and uploading videos is now here.
The app is still in beta though, so there are a few known issues that the devs listed, I also added some issues I noticed while using the app:
-Can't sign in with Facebook.
-The "share to" functionality does not work.
-No wordflow (swipe keyboard) when leaving a comment
-display doesn't auto-scale when you dismiss the navi-bar
-It crashes during creation work flow
-Other stability issues
Of course, these issues will be fixed in subsequent updates. Let's hope they don't abandon this app like the did to the last BETA version.
You can check it out for yourself:
Download Instagram for Windows 10 Mobile