Depends how people are getting to your AMP page.
At the moment the top stories features is the only place using AMP - unless your website directs people to the AMP pages? So in that sense AMP is only useful for NewsArticle documents at present. Though Google have said this list is likely to grow, quickly.
However if the AMP page is your main page then users will still benefit from the fact your AMP page is fast - even without the NewsArticle structured data tag. Though personally I don't think AMP pages are ready to (or should ever be) completely replace standard HTML.
Will be interesting to see how this changes in future as others (e.g. Twitter) start to integrate AMP pages. Though I'd imagine they'll likely follow Google's lead and demand the same requirements as they do.
Edit 1st March 2016: Google have added a page to the Structured Data site explaining requirements to get in the top stories section: https://developers.google.com/structured-data/carousels/top-stories