Good questions!
I'm going to move this thread to the e-Publishing category... for the benefit of all readers & Members
does offer stats on Open Rates, and much more. It is a double-opt-in compliant service, also, which offers you protection with all of the current & pending laws. It is also one of the top mailing list managers in regards to delivery - it delivers a higher percentage of email than most (less chance of being blocked or blacklisted at the ISP level).
I like the fact that I can access my account and send messages from any computer - home office, laptop, library, you name it! Very convenient. I can download my database in Excel format at any time, so I keep backups and can run queries on my list easily.
You can customize your verification messages, autoresponders, confirmation pages, etc - its very flexible, and the service has been exceptional in my opinion. This is the service that was recommended to me by a professional that I trust - and I understand that most "top marketers" use aWeber to manage their lists as well.
I was sold on the recommendation alone... but have been very happy with their service since I made the switch in January. My delivery & response rate improved dramatically!