It works very well. Could not find a better plug in for the newsletters. Easy editing, powerful, themes you can choose from.
The free version has many nice features including basic statistics for who openend/clicked on your newsletter. The main limit is the maximum 2000 subscribers, which is enough for many web sites with smaller boards/traffic.
If you need a higher amount of subscribers or other premium features, then the price tag for the Premiun version isn't exactly low if you work on a free / non profit web site. For a commercial activity it's worth every penny.
What I miss is the justified alignment in the text layout. I use it almost always in the articles and in the newsletter I am limited to the traditional left, right or center.