They have tweaked a few things to improve performance to a level it should already have been at anyway and moved a few things around while they were at it. Microsoft have pretty much confirmed that. Why is everyone getting on their high horse over it?
Sounds like the posts about Vista in the early days claiming it was just "XP with some new graphics and a bunch of changes i can't see or care about".
So far we've seen 7 is based on Vista but is quicker, fixes assorted "problems", changed menus to be more intuative, boots quicker, has changed how UAC works to be more user friendly but keep security, adds Windows Media player 12 along with native support for DIVX, XVID, x264, adds bluetooth 2.1 support, updates all the "freebie" apps like paint with Office 07 type ribbon interface, removes the extra apps like photo gallery by default to reduce bloat (allowing you to download and install free live versions instead if you want them), adds jump lists, changes the way the files system works to be much more SSD friendly, Bitlocker for mobile (USB) storage, adds multi touch support, task bar app grouping, updated icons and graphical touches, optimisation for battery life on laptops already at ~10% better than Vista SP1, natively supports and will mount .VHD files, and a whole bunch of other stuff... Not forgetting 7's not even in beta yet and the PDC build proved there was stuff MS was disabling/not showing yet...
MS have said 7 is an update release building on the architectural changes made in Vista.
The problem is, it's an OS and really only serves to be an interface between hardware/resources and your apps it's going to be tough to change much without breaking stuff.
Given your disappointment, what else would you have wanted to see changed?
In terms of previous comsumer desktop OS comparissons I would group them as:
Windows 3.0 major change, 3.11 update to 3.0 platform
95 major change, 98 update to 95 platform
(There's a bunch of stuff in here at this point for non consumer desktop OS like 3.5(1) to NT4, to 2000 which doesn't really map for consumer desktop OS)
2000 major change, XP update to 2000 platform
Vista major change, Win7 update to Vista platform
OK, so I know it's not exactly the way things works but it's about right to set expectations.