I've used a number of high-end (read expensive) emailing tools and I was very pleasantly surprised with the functionality offered by Mailchimp. Scheduling emails, dynamic content, social media intergration are just a few of the features that it offers. Mailchimp includes a lot of templates also for the quick email. We are also using the Survey Gizmo integration and have used their APIs to build our registration list.

The only negative I would say that I've found is on the types of advanced filtering that is possible when creating segments. It's not possible to segment on previous user actions (opened, clicked, did not click...). 

Definitely worth checking out!

Easily the best Email Marketing tool.  So many built-in features, plus the ability to keep adding so many people to your marketing list and create customized emails is amazing.  I love the auto drip email ability, testing, social aspects, and how they keep coming up with new features all of the time.

I recently used MailChimp in a political campaign and found it incredibly useful and easy to use for simple emails. What I also enjoyed about MailChimp was how fun it was to use and their constant innovation, always adding new features and updates. The incredible things they do with email tracking and deep analysis of email drafts are amazing. I also found the pricing competitive. I'd say the main drawback to MailChimp is their email editor, which I found difficult to use at times. When I was doing simple emails it was great, however, for more involved emails with lots of graphics and HTML formatting it became difficult at times. Other than the formatter I'd recommend MailChimp.

Beautiful easy to use templates! Easy to use interface. Constant Contact better start updating their interface soon!