We've reached the point where we can reasonably expect a new release of Apple's operating systems (iOS for handheld devices, OS X for computers) every summer, and here they are again, right on schedule.
Should you upgrade? Well, you can't — not until the fall at the earliest; this is just an announcement of things to come. When fall rolls around, if you're an early adopter, of course you're going to upgrade immediately anyway, regardless of what we say here. For everyone else, give it a month for all the early adopters to finish the gamma testing for you and then download the +0.1 bug-fix release. This will all be available thru the App Store, and your currently installed operating system will undoubtedly remind you of it from time to time until you do.