I think that there is a difference, but it's been way, way, way overstated. In additional to frame material there are many factors that affect ride quality. Your tires, for instance are much more significant. If you are buying your first of second road bike, worry about how you fit on the bike. Your budget will drive the rest of your purchase decisions.

I own 2 road bikes, an old butted steel Bridgestone RB2 and a newer aluminum Klein Quantum Race. I'd say that the Bridgestone has the comfier ride, but it also has a Brooks saddle and tires that are 5mm wider with 20psi less air pressure. Absent those factors I doubt I'd feel very much difference.