I have been using GetResponse for my SEO Team training series and have had a good experience with it. No issues with using or delievery.
I think GetResponse and Aweber are kinda neck-n-neck as far as 'who is the better service'.
Now that my blog redesign is nearly done I'm going to be releasing that to the public and also starting a newsletter based on home based business common sense, to start building my list.
I agree with Fendi that the one on your hosting account is a great option. It gives you more flexibility espeacially for importing email lists. The subsription ones that you pay a monthly fee for, will send out an opt-in message that has to be activated before you can send out your email campain letters. There is also an auto responder that can be installed on you PC.