I installed to a raw unformatted partition on my main system. Install took quite long because there was a lot of stuff downloaded, some unnecessary I think, like language packs I don't believe I need. Other than that install was easy and straight forward.
Graphics drivers that are made available still leave a lot to be desired for me. It wasn't possible to change my monitor refresh rate which is essential for my monitor and GPU (the one in my sig). I tried two proprietory drivers from NVIDIA, recommended by Ubuntu. Attempting to save the way I eventually got the GPU acceptably setup was impossible, so each time I booted to the system I had to redo the screen resolution.
When unsuccessful changing the default GRUB boot loader menu entry, so that it would point and boot to the Windows 7 bootloader, using the exact same procedure and commands as I did for 9.04, I zapped the installation, ran a fixmbr from the XP CD to remove GRUB and deleted the two partitions Ubuntu creates during installation. What's with a new beta GRUB version being used with a public release?
I have no intention of messing with Ubuntu again until a few basic things don't need one to do handstands to get working.
Otherwise I was quite impressed but didn't see any big change from Ubuntu 9.04. Maybe it takes a much more experienced Ubuntu or Linux hand to tell. Windows 7 and OS X needn't feel threatened at all in my opinion, not just yet anyway.