The two biggest areas of focus for this release are the new Universal ATA driver and improvements in the USB stack. The new Universal ATA driver adds support for Serial ATA disk drives as well as partitions greater than 8GB. The improvements to the USB stack increase the compatibility with USB keyboards and mice.
There are still bugs in these areas, though. "These features are still under heavy development and have several known bugs," the ReactOS team warns, "but their inclusion should allow more people to run ReactOS on real hardware and are part of the extensive work to make ReactOS usable as an every day operating system."
This release is still considered alpha quality, so know what you're getting into. You can grab the new release from the download page.