Practically every Joomla extension claims to be easy to install, easy to use, and deliver loads of functionality, so it's very difficult to choose which extension to actually try even with all of the available reviews. I'd like to say that AcyMailing lives up to the hype! I've only installed the standard version so far and I haven't had a lot of time to dig into it yet, but I was able to install it and successfully send my first newsletter within 15 minutes! The admin user interface is fantastic - it integrates seamlessly with Joomla and it's very intuitive. Within an hour I was even able to create my own custom template and successfully send a newsletter using that. I'm looking forward to using more of the features and most likely I'll be upgrading to the Essential version soon.
Congrats to the developers. This is a great product!