What's new in this version, you ask? Well, it launches quickly, it uses tabs, you can check a number of different email accounts (in addition to your AOL account), AIM is built right in, and it is customizable. It has that unmistakable AOL look to it (which is either a good thing, or a bad thing depending on who you ask) and it was fairly snappy on my iMac. I wasn't able to test out all the features because I don't actually have an AOL account myself, but it is in beta and that means there are bugs to be encountered.
I'm sure a small number of Mac users are happy to see this release, but I'm more anxious for an updated version of AIM. Mac users are a full 2 versions behind our PC friends on that front (though I recommend you check out Adium for all your chatting needs).