Campaigner

Campaigner is easy to use, and doesn't require a lot of technical knowledge to get started (although it certainly helps). Their technical support team is fantastic, though, unlike most other SAAS. They actually have people you can talk to - and they are consistently awesome.

We use it mostly for email marketing. The reporting is great, and everything (except for the 'cons' below) is pretty intuitive.

Campaigner is missing some critical functionalities that are becoming deal-breakers. Fairly simple things like integrations with Wordpress. One of the biggest gaps is the complete inability to easily create attractive sign-up forms for websites or popups. They have some templates - which are just, well, horrible.

Keeps track of membership and statistics of who opened the email and clicked one of the links.

Designing a notice. After a 1 year break, I found the development of a notice aimed more at commercial groups and not technical societies. Trying to reuse a previous notice with edits for the next luncheon talk was not obvious. It used to be easier. The templates are not useful for notice of meeting for a technical society. The help section often leads me on a merry chase looking for information. A series of tutorials would help. I do not look forward to handing my position to a new person this year.

We use it for simple email blasts to our neighborhood association. We don't use it for marketing campaigns, so therefore do not have the need for some of the functionality available with Campaigner. For our needs it works.

Ease of use. It is not intuitive, and they haven't done any kind of software or GUI redesign since we started using it (6+ years ago).
Making a template should be a lot easier than it is: Creating and editing templates has a lot of old graphic (frames?) technology that makes for a frustrating experience when trying to line up text blocks with headers, footers and images.
Writing an email with attachments should be easier. Having to upload a file/image to the media library, and then importing it into your email is a lot of steps. Instead, allow a person to add a file/image to an email note in the same simple fashion as any other email client works: add a paper clip button and allow us to select the file to add to the note. That seems like it should have been done a long time ago.
Also, if you accidentally remove a person from an email list, you have to call up Campaigner support to get it fixed; you can't manually fix it yourself. Very annoying.