Plenty, especially when you see a broadcast in pure HD, or have watched some of the great programming in HD already available over the air (I've not been impressed by the compressed cable TV versions, 'though it's often superior to SD). A key reason why we're happy to have a standing order for the new Xbox 360, as content looks incredible and very compelling when this system is paired with a good HDTV.
MSN Tech & Gadgets has a linked article today to the ten myths of HDTV where there is still a lot of confusion among consumers and technophiles.
Of course, this may be moot as we could easily see the date to switch over to digitial TV extended yet again from the latest DTV transition hard date of April 2009. From what I've seen in the press, the date may be extended again as the swtich over could be postponed until at least 85% of homes in an area are able to view DTV broadcasts.
There are plenty of benefits to make the move to HDTV. And with the way prices on premium sets seem to drop almost in lock step with Moore's Law, I should soon be able to find a 50" HDTV flat screen for the price of a 27" LCD TV today.