And, as many people on the net have already said: It will be a VISTA of OS X..
Contrary to all previous OSX releases there is hardly any reason to switch from SL. In fact, the trouble of migration outweighs benefits for us.
I'd be "downgrading" my new Air to SL when it comes.
And those that are saying this is Apple's Vista are utterly wrong.
Vista gained its reputation for being largely broken at launch. Performance was dreadful, serious issues affected basic operations such as file copying, User Account Control was far too intrusive, drivers were either very early or simply didn't exist... the list of problems went on and on. To be fair Microsoft addressed many of those issues as time went by and the Vista many people are still running today is a much improved beast compared to the launch product. The damage was already done though and people stayed away not because it didn't offer anything new but because they viewd it as a broken product when their existing XP systems were working fine. Of course the rather large price tag for upgrades may also have had something to do with it...
Now on to Lion. In many ways this is the biggest set of improvements to OS X for several versions. Versions, Resume and Auto-save alone represent a major change to the user experience and a welcome one. Improved multi-touch gestures, launchpad, mission control and full screen apps are all interesting features that will work very well for some and be more-or-less ignored by others. Considering this is a mature desktop OS (let's face it, almost all current desktop OS's are now mature products with very little missing functionality) this is a surprisingly large move forward.
I can certainly understand why certain users can't see any major reason to upgrade but ultimately that's personal preference / requirements rather than an overall judgement on the product. For the average user there's more than enough here to justify the very small outlay. Heck even Paul Thurrott has given Lion a positive review! "Apple's Vista" it most certainly isn't.