Allen Browne has put together a nice resource page on Access 2007. I'm not sure I completely agree with the statement about too buggy for serious use--guess that depends on your definition of serious use. As with any major release there are some bugs that slipped through (the team will focus on fixing the critical issues in SP 1) but I feel pretty good about the "What's fixed" list. Most of those issues have been a pain in the side of Access developers for a very long time. Personally, I find it painful to use Access 2003 after spending so much time using the new functionality. 

 "The most significant release in 12 years, Access 2007 introduces major new functionality in both the engine and the interface. Seasoned developers will discover new things are possible, and casual users will find more things within their grasp.

With so much new stuff, it is no surprise that the new version has many bugs. It will be a great product, but the initial release is too buggy for serious use."

Here is my favorite section:

Issue Solution
Security dialogs

Every time you opened your database, Access 2003 tried to convince you that was a bad thing. Access 2007 solves this by introducing Trusted Locations (Office Button | Access Options | Trust Center | Trust Center Settings.)

Mouse Wheel

Developers often coded to disable the mouse wheel so it would not scroll records in Form view. Access 2007 scrolls in Datasheet and Continuous view, but not form view. Use the new Mouse Wheel event if you want the old behavior.

Email in Hyperlinks Previous versions prefixed "http://" to all hyperlink fields. Access 2007 recognises email addresses, and prepends "mailto:"
Percent format If you type 5 into a field formatted as "Percent", Access 2007 understands it as 5%. Previous versions interpreted it as 500%. (This workaround is no longer required.)
Default Value (number fields) You no longer have to remove that annoying zero Access used to assign to the Default Value property of every numeric field you created.
Reserved field names Access 2007 recognises the most common field names that cause problems (e.g. Name, Date, Month, and Year), and warns you (in table design.) It responds to only a very few reserved names, so you still need this utility or list.
Picture + Caption Display both a Picture and a Caption on command buttons and tab controls (but not toggle buttons.)
Autofill (datasheets) Previous versions attempted to guess the number you wanted when entering data in a datasheet. This annoying behavior has been removed.
Imports Several issues solved, such as the ability to choose columns and specify data types when importing from Excel.
Internal margins Scroll bars now work for controls with internal margins, and size-to-fit correctly. Controls now have padding as well as margins.
Filters Several filter bugs fixed.

http://allenbrowne.com/Access2007.html

Updated post with whats fixed information 1/20/2007.