For one thing win 7 has a sane memory manager, like XP XP X64 will start pimpslapping swap even with plenty of memory left while Win 7 will try to avoid swap and will use unneeded memory for caching to help speed up response.
I've never seen this, but then with 12GB of RAM, I don't often get close to using that much for apps (cache, etc., of course). Maybe with less memory or a much larger workload than I have (which includes VMware Workstation running a couple of local VMs and displaying 4-5 remote VM consoles, audio and video editing and encodling, and non-bleeding edge games).
There is the increased security of low rights mode browsing and running everything under user instead of admin
If you don't use IE (which I haven't for years), and you constantly have to run full admin tasks, you don't get any advantage from either of these.
, breadcrumbs and jumplists make it trivial to get back to what you were doing previously,
Breadcrumbs are only a fraction of a second faster than just clicking "back" a few times or editing the path manually. Also, you lose the "up" button, which is the navigation I use more than "back to the last place". Jumplists would be great if you could edit and create your own without arcane knowledge of the filesystem. There are so many apps where the jumplist items are insanely stupid, like VMware Workstation, with the only item being "Create a new virtual machine". Outlook (a Microsoft app) doesn't have any jumplist, where things like "new eMail" would be insanely useful.
I have Win7 at work, and nothing is pinned to the taskbar, because I rarely have apps that need only one instance (which is the default if you just click the pinned app). Pinning to the start menu, the old "quick launch", and "Classic Start Menu" with custom shortcuts to give me back a nested, organized structure do what I need. I do like the "search" on the new start menu, though. And, don't get me started on the uselessness of "Libraries". I want to know where all my files are stored...I don't want the GUI shell to hide that info from me.
The actual OS of Windows 7 really doesn't offer a lot more than XP, although it does have some nice things that keep you from having to download something to do the job, like real-time TRIM support for SSDs (in XP, a scheduled job using the manufacturer's "toolbox" does good enough for real-world use), built-in UDF 2.5 support, built-in CD burning (although ImgBurn is still much better), etc. Notice that most of what both you and I list are user-space items that can be added to XP.
As for negatives, some of the extra security (like TrustedInstaller) makes for a pain in the butt if you want to customize some things (like standard MMC layouts). And, although it is easy to move an individual user's profile directory from C:\Users, moving all user data that can get large (C:\Users, C:\ProgramData) to another disk isn't nearly as easy as in XP. The tools to do the move in Win7 assume you are deploying many installs, so the task is much harder if you are just doing one machine.