It's relatively easy to use. I sent my first newsletter with it today. Everything that I've needed to do in the way of importing and linking to wordpress accounts has been possible. Everything I wanted to do with look and feel and messaging has been possible.
I gave it 4 stars instead of 5 because the UI could use some refinement. It's sometimes tricky to find exactly what I'm looking for within the plugin. And some of the features require explanations or reading to figure out exactly how they work. But it looks like a relatively new plugin with an active developer so I have no doubt that it will be up to snuff in no time!