Probably the worst code I've ever seen, copy and paste gone crazy, buggy as hell in tracking where it is up to, just nasty and I really wanted to like it. Refund was no problem though.
We've also been using Sendy and I agree, the code is far from perfect and we have spent countless hours either fixing some issues or adding much needed features, making it actually usable for SaaS (sentopia.net), will need to move away to something better in the near future, this maybe a good start!
Functionality wise, it seems the same.
ninja edit: it made me sick because it was ugly, didn't feel secure, and it took me ages to make the changes I needed to make.