So GitHubReminder was my first Hapi-based site too. Fwiw, this is what I've taken away from it:
* There's definitely less boilerplate compared to Express;
* It has a really nice validation abstraction baked in;
* I didn't use it, but there looks to be some nice security stuff in there too;
* When I got stuck I found it quite difficult to work out what the problem was, there's obviously much less of a community than there is around Express and some of the docs are a bit terse.
But I'm not hugely experienced with Node or with building websites generally, so that last one may have been more of a personal limitation! :)