Windows 7 is proving a divisive subject even in its infancy. One example: Last week, reviews from CIO.com's sister sites, Computerworld and InfoWorld, offered radically different opinions about what Microsoft has in store for the successor of Windows Vista, expected to ship in early 2010.

Depending on where you look, Windows 7 is being called a savior for the embattled Vista, or a disaster waiting to happen. Regardless, certain interface features in Windows 7, whether brand new or streamlined, have been mostly applauded by experts who have tested the pre-beta.

Which features are the most interesting and controversial? Here are five that deserve your attention:

Revamped User Account Control

Vista's well-intentioned security feature UAC (User Account Control), perhaps the operating system's most despised feature, became an easy target for Apple's "I'm a Mac" ads. Users were driven nuts by UAC's frequent pop-up prompts seeking confirmation before allowing programs to open.

In Windows 7, Microsoft gives more control over UAC to the user, so there will be fewer prompts. If the user makes any of the changes that Vista has been prompting, such as changing the date or time, Windows 7 will leave it alone.

In his review of the Windows 7 pre-beta, Computerworld's Preston Gralla commends the improvements made to UAC. "It rarely gets in your way—you get a prompt only when a program tries to make changes to your PC. If you make them yourself, it allows you to go ahead."

With Windows 7, Microsoft has dropped the "on or off only" approach of Vista and made UAC customizable.

There will now be four settings: Never notify; only notify me when programs try to make changes to my computer; always notify me; always notify me and wait for my response.

Improved Taskbar

Microsoft's new Windows 7 taskbar was demonstrated at the company's recent Professional Developers Conference, but was not part of the pre-beta software handed out to attendees. Still, and probably because it's not included in the pre-beta, it's one of the most-discussed features.

Based on screenshots from the PDC demo, the new Taskbar has been given an overhaul. It does look notably similar to the Mac OS X dock, but reportedly includes unique enhancements such as the ability to display all running programs in a thumbnail list.

If you hover over a thumbnail with the mouse, its full-size window will appear on the screen. In addition, mousing over a thumbnail turns other windows transparent to reveal the window you selected.

Large icons in the Taskbar will launch programs, and you can rearrange the icons however you like. The Quick Launch bar of Vista will cease to exist and be incorporated into the Taskbar.