To me is quite a deal breaker so far. The code on our website with Amail is really really more simple (no template engine for instance). And they give you out of the box a ton of analytics (geolocalization, bounce, click, open) even for singular mails.

Like Amazon SES on steroids.

P.S. Not affiliate with amail, just an enthusiastic user. We are using that at CoffeeStrap and we just saved a lot of time in development.