This plugin has potential, but there are a few show stoppers that I wanted to share with anyone spending time testing all the newsletter plugins out there. I addressed these directly with the developers, and they say they're taking them into consideration. If these things are addressed I will update my comments here. In the meantime, I hope this gives some insight and saves you some time. Hopefully all of these things will be addressed very soon.
The biggest thing is that it doesn't fully support names. Yup, names. As in, your subscribers' names. You can collect their email addresses, but not their names. Unless you want to manually enter them in the admin screen. Obviously that's unmanageable. Being able to collect subscriber names is a core feature of any newsletter software. It ranks near the top in importance, yet it doesn't exist here.
Also the code has been minified to render it obfuscated, making it practically impossible to know what it does, or to modify if it needed, a key trait of GPL software. I believe this also violates #4 on the WordPress plugin guidelines listed at http://wordpress.org/extend/plugins/about/guidelines/ .
You cannot control the display of the subscription forms so that they match your site design. It inserts an unintelligible block of base64 encoded text into your post or page.
It's also apparent by looking at writing style that the developers are spending time on these forums generating fake reviews. The sad thing is, if they'd implement name support, allow for customization of the form display, and stop compressing the code to make it unintelligible, they wouldn't need to do this.
It would be the best newsletter plugin around.