My drive wouldn't let me partition my drive so I just took a risk and installed it over Yosemite.
SMOOTH.
Granted I have a non-retina MBP with hd4000 and never really had lag except under load in mission control... but all the animations are just faster and smoother. Mission Control layout is fantastic now. I believe it was the blur that slowed it down so much, maybe the app icons too? I'm not sure but they're both gone and it makes a big difference.
Scrolling feels faster too, it was smooth before but I think they just sped it up.
What can you say if you compare mavericks and snow yosemite?