OpenOffice 3 has been officially released, with one of its biggest enhancements being support for file formats in Microsoft Office 2007.

The debut of the open source productivity suite follows a three-year development cycle. Nevertheless, some reviewers questioned whether the upgrade was sufficient to be billed as a full upgrade.

Released on Monday, the upgrade attracted enough attention to overwhelm the OpenOffice.org Web site. On Tuesday, the site still appeared to be having trouble with the load. "Apologies -- our Web site is struggling to cope with the unprecedented demand for the new release 3.0 of OpenOffice.org," the site said. "The technical teams are trying to come up with a solution."

The software suite combines word processing, spreadsheet, and presentation tools similar to the Microsoft Office suite. The open source version, however, is free, making it an attractive alternative for people or businesses that need only basic capabilities.

The biggest improvement to OpenOffice 3 is the ability to open Office 2007 files. However, some files, such as .docx, .xisx, and .pptx, can only be read. The second major enhancement is a new version for the Apple Mac. The upgrade installs and runs like a normal OS X application.

However, the new features and better performance of the upgrade failed to impress some reviewers. "OpenOffice 3 might as well be OpenOffice 2.5," said Rob Pegoraro of The Washington Post. "Nearly all of the things I liked and disliked in that release live on in this edition."

Linux Format, a British magazine, also was not sure OpenOffice 3 could be considered a full upgrade. "Does it justify the jump in major version?" the magazine asked. "We're not convinced, but the 2.x series has been around for a while and this release does present a fresh face. ... On balance, the new OpenOffice.org release is a step forward, and if they can speed it up a bit, we'll be more than happy."