I've been kicking the tires on an early beta version of SalesLogix 8 and from a users perspective, I would call it a vast improvement in overall performance and responsivness along with a needed refresh of the entire user interface. The bain of all CRM systems is user adoption and it's clear that Sage focused on improving the overall user experience in this release rather then adding more features.
It still has the framiliar look and feel of the previous version but Sage has clearly sprinkled fairy dust on it which has resulted in a simpler, cleaner, quicker overall interface. Many of the screens, menus and toolbars have been re-worked and it just seems more intuative and polished. Menus and icons have a more logical layout and the list and summary views now have checkboxes next to rows to make it easier to multi-select vs. having to shift/ctr-click. They also improved the Group Management interface which is now much easier to use and understand. They've added native integration with Google Docs in the Attachments tabs which is pretty cool.