So far it is working perfectly. Pretty easy to define viewable content in articles with {jugaacess MemberGroupName}content{/jugaaccess}. My reasons for only rating 4/5 are as follows:
1. Requires legacy support. Until Joomla! 1.6 is released with a real built-in ACL, I need this extension (it's the only one reasonably priced that actually works for me). However, I would really prefer a J!1.5 native extension.
2. Assigning content to pre-existing groups is easy. Creating those groups, assigning them to users, and assigning entire content pieces to groups, isn't especially hard, but is VERY tedious. It would be nice to be able to filter the list of items by more specific types, such as articles and menu items. Would also be nice to have a listbox of available groups at the top of the user page, and be able to select a group from the list, checkbox to select which users to add to it, then have an "add selected users to group" button.

The fact that this, being an alpha release, has had ZERO bugs worth notice compared to the massive number of problems I had with jvbPlugin makes it a vastly better product even considering the current lack of many features. The ease of installation is only a thousand times easier than that of jvbPlugin, too. And JFusion is free :)