This is good! I've just installed it on our band website and it beats the socks off the previous mailing list software I had (newspro). I'm fairly new to the whole PHP lark, but I got it installed with very little trouble - the only problems I had were with multiple passwords and usernames for the databases, directories and access - due to my memory rather than the program! The only thing I'd say initially is that it's tricky to customize the public pages. I want to keep the images and links provided, but I'd like to change the style and colours to fit in with the rest of our site... but I'm still fiddling with this at the moment.
In general, so far it's excellent!