Have taken this route to/from the US a couple of times although the last time was about 6 years ago. I really recommend it, Icelandair offers a good service, the airport is a dream, Reykjavik is a lot of fun if you have to stop over. The only downside really is the increased flying time and the fact that their flights do tend to be full most of the time.
Hopefully you will get more recent feedback from others.