I heard it happened to some people... well, it's still a beta, so it's entitled to the occasional hiccup

I installed it yesterday on my laptop (specs a few posts before) and I'm really impressed - everything works like a charm, the only drivers I had to download from Toshiba's website were the Bluetooth stack and card reader, everything else either worked from the start or downloaded via Windows Update. The only thing I haven't tested yet is HDMI, but it is present on the list of audio devices, so I'm pretty certain it'll work.
The system boots a bit faster than XP, significantly faster than Vista, and is very fast and responsive (even with Aero turned on, and we're talking Intel X3100 here).
The new taskbar is really cool, it's much better organized than before, gives quick access to everything. Things like player controls on WMP window miniatures and a progress bar overlaid on top if the IE or Windows Explorer icon when downloading or moving files are a nice touch. The miniatures could be generated faster, though, there's too much delay.
Apart from eye-candy, there are also some other additions which aren't as flashy, but are very useful. The Task Manager now has a Services tab, where all the services are listed and can be stopped or started; there's also a butoon that opens the services.msc applet.
Another great addition is the Resource Monitor - it's a tool that gives a lot of information about CPU, memory and HDD usage, network traffic and other stuff. It's really detailed, and I'm sure will be useful for troubleshooting.
Last, but not least - the new Windows Firewall. Forget the simplistic thingy that was in Windows XP - this one is totally configurable, with a ton of already existing rules (separately for inbound and outbound traffic) and the option to create new ones, based on application or port (or range of ports), allowing not only to block or allow traffic, but also do it only for selected users, computers in the network or applications. At the same time the basic interface is simple and unobtrusive, so less experienced users can leave all the aforementioned stuff work in the background, while advanced users will probably tweak the firewall to their liking.
Wordpad and Paint received a new interface, with a ribbon similar to Office 2007. It's a change for the better, because all the options are now visible (they're on a single tab). Calc was upgraded with a programmers and statistical view, as well as a unit converter and date calculator.
BTW. Wordpad no longer has the option to save in DOC format (there's RTF), but can save in OOXML and ODT

In my case, the system takes about 10GB of HDD space, and eats up about 800MB of RAM with some apps running (WMP, Wordpad). CPU usage, when idle, is around 0-2%, with the occasional peak to 5% (1.86GHz Intel T2390 Dual Core).
All in all, I think Microsoft did things right this time, and if they don't screw the final version up, I'm moving from XP as soon as Windows 7 hits the shelves.