It's hard to go back once you've made the switch, although initial impressions can be disappointing.
Terrestrial HD broadcasting is disappointing - full of artefacts and poor compression.
Discs on the other hand are another matter:
I started with HD-DVD (my preferred format) Then Blu-Ray
And now I just got the Sony PMW-EX1 camera which shoots stunning footage in 1080p (see some showreels on philipbloom.co.uk for what sold me on this camera) and captures everything to PCI Express cards with two "hot swap" slots on the camera.