Friend of mine just put these on her Prius (had Dunlops that were dry rotting after only 3-4 years!), her mileage is "about the same." She doesn't keep close track. Noise: quieter, handling, well, it's a Prius, so I don't know how much you could say about that.
2004 Honda Civic Hybrid "Eeyore" @ 49 mpg
-MaxIMA, OBDIIC&C, IMAC&C, Lower grill block
RIP 2000 Insight, 40k miles @ 69.2 mpg
2000 Insight, AKA "The Basket Case" or "The Go Pod" @185k miles @ 63.5 mpg
-IMAC&C, OBDIIC&C, Scott's aero panel, grid charger, cheapo sound system