I recently got up to speed with a rails app remarkably quickly and I agree with all of these points. I found testing wasn't really a joy, but it was less painful than any experience I've had in the python or PHP world. Mailer previews are actually very cool, too. It's not a game changer but I liked having it and it came in handy.

ActiveRecord was also surprisingly slick. I'd previously mostly used Doctrine and over the years I've mostly come to dislike it. AR was fine though and had some features I liked quite a bit. Scopes are really neat. Like any ORM though there are plenty of double edged swords all over.

I'm actually keen to work with Ruby more since working on that project. Rails is really nice, even if it's a lot different from how I'm used to working. It felt very productive.