I guess there's some improvement, but having experienced the transition from mono VHS into a RCA splitter, to HiFi VHS into a ProLogic decoder, to Dolby Digital/DTS on DVD into a 5.1 receiver. Those were all huge improvements over the previous generation, there'd be no mistaking one for another. But this lossless audio on Blu-ray into a 7.1 receiver, is only incremental.
I've not done any A/B comparisons between DVD and Blu-ray releases, but I didn't do that either with the previous iterations; it just wasn't needed, the change was so obvious.
Of course I've yet to upgrade the rest of my speakers from the DD/DTS days, and haven't upgraded my ears either. So I may be at the limit of what I can resolve, but I don't think so.
(On the other hand people who say they can't tell the difference between an upscaled DVD and a Blu-ray disc in terms of picture quality have to be blind, or watching a 20" television.)
