This plugin has been really great for me. Even before the 3.4.1 upgrade, I considered this an absolute must, and always tell people about this plugin when they are looking for an e-newsletter solution.
The 3.4.1 upgrade was nice, but I noticed a few bugs. When copying a newsletter, the original recipient count is not retained on the original newsletter that was copied. That's a problem if I want to track how many recipients I had each time.
There's also a ton of functionality that I don't use, which is why I haven't gone with the Pro version yet. Some of the typos are disconcerting, though I understand the creator is not a native English speaker. That isn't an excuse in my book. Ask users to proofread, and I am sure many of us would help.