Doing an in-depth review is a bit outside of the scope of what we do here, but I wanted to make sure y'all knew what I thought, so if you've got time you should read the massive review of it that I helped write for Anandtech. A quote that sums it up:
"For those of you worried that Apple's "back to the Mac" marketing push would result in an OS X version that sacrifices functionality in favor of imported iOS features and reduced capability: those fears are, by and large, unfounded. The iOS-inspired functionality is mostly laid over top of a foundation that's more or less OS X as it has been since Leopard - a solid, mature and full-featured desktop operating system.
That said, the usefulness of individual Lion features will likely come down to your individual needs and work patterns. Most should appreciate solid new features like Versions, the new Mail, and the much-needed enhancements to FileVault, but features like Launchpad and the UI overhauls of iCal and Address Book are of dubious benefit to users, and other heavily-promoted features like multitouch gestures and the Mac App Store are already available to Snow Leopard users.
So go check it out!Even so, at $29, there is really no reason not to buy Lion..."