Two days ago I volunteered for the early adopter Corporate Vista rollout. I'm typing this from Vista as we speak. I'm still in the process of getting my data and programs back on my machine, but I'm running a mobile Precision M65, T2600 2.16GHz, 4GB RAM (3.3GB reported thanks to 32-bit OS), Nvidia Quadro FX 350M.
My Windows Experience Index is 2.0, unfortunately, with the graphics the limiting factor. I'm pretty sure that's because I'm still running the driver from the OS and haven't loaded the Nvidia driver.
My monitor is a Dell 2007FPW at 1680x1050, and Vista looks NICE. Widescreen monitors are the bomb with Vista.
Excel 2007 is pretty much the same usage-wise, and I thought I would have a harder time getting around the Ribbon, but I think I like it. I haven't had much to do with the rest of Office 2007 but I'll be sure to post it. I really like Outlook 2007, especially the calendar layout. A To-Do Bar is present within many sections of Outlook, and I like it more than previous editions.
This is all pretty subjective right now, without screenshots, but I'm almost late for a meeting. I'll try to put more as my experience grows.