The biggest strides I see from D/W have been largely technical, but I can't get over how much more naturally they seem to move then before (it's particularly true when you compare it to the Tango, which never reached that level, imo). I actually think they have the better SD between the two (it's more cohesive) and they really have worked on their performance/projection. What I want to see more is connection to each other. I thnk I could watch one or the other and see no difference then when I watch both (this is true in both dances, but here it's more noticeable). Artisticallly.... okay - I've actually seen Die Fledermaus more times than I've seen Funny Face (mainly because I wanted to watch that first rotational lift over and over again), but when I imagine the dance, I can't place it with the music. Now, I'm not as familiar musically with the former as I am with the latter, but there's no difference in D/W's waltz with or without music.
YMMV here, but I feel the opposite. That dance totally matches up for me to Die Fiedermaus. I can't see that same waltz being done with another waltz, say Carousel or even the pieces they skate to last year. I'm not a waltz expert so I can't articulate it well, but that dance equals Die Fiedermaus -- namely because of Charlie and Meryl's personality.
I think another poster said it better to me -- it's a classic waltz, but with a bit of personification in it. That's why I think it works so well.