I think it's tremendous. I've been listening to them on myiPod shuffle the last two days during my exercise. I'm a geek, so I put on a bunch of science-related podcasts; a couple on Einstein (as this is the 100th anniversary of Special Relativity), and a bunch on space (e.g., the comet we're blowing up this Fourth of July).
I could easily see a routine of loading up the days news summaries, ESPN, and a couple of other programs...there are 1,000s of them out there.
I am having some problem with the implementation on my shuffle, though; sometimes I'll load it and the podcasts won't play. I suspect there are still a few kinks.