I've started building an app for Instagram and would like to know. Apart from the newly introduced sandbox and app approval requirements I haven't noticed any major pain points yet.
It's true that most libraries are only seldom updated, but on the other hand the API doesn't change much and it's REST with OAuth after all.
That's pretty quick actually, didn't expect that they'd be so fast.
Edit: I'd be pretty interested if other developers could share their experience with the approval process too.
Yes, Instagram legally owns your data, but now they are actively preventing you from accessing it as well.
"I want to display hashtag content and public content on my website."
"This use case is not supported. We do not approve the public_content
permission for one-off projects such as displaying hashtag based
content on your website. As alternative solution, you can show your own
Instagram content, or find a company that offers this type of service
(content discover, moderation, and display)."This is the kind of thing that causes people to circumvent their API management layer...