I've been happy enough but not quite what I expected. I'm averaging 19 - 20 mpg on my daily 10 mile each way commute (most of which is interstate). Driving 70mph I can get about 24 mpg on the interstate but it's hard to keep it at 70mph, especially in Atlanta traffic. The 3 stop lights between my apartment and the interstate and then the 3 more between + 1 stop sign between the interstate and campus are what drag my mpg down. I'm confident that on a long road trip I could get upwards of 23 - 24mpg, I doubt I'll ever see the 25mpg highway listed on the sticker.
I'm completely happy, gets the same mileage around town that my V6 acura CL did. I get roughly 19-20 on my daily commute which is almost 70 miles of highway and city driving w/ a good amount of stop and go traffic. I did a run to the casino on friday, 200 round trip, got 24.2 mpg
I have full faith I will see 25+ on a few long road trips I plan. I've seen 30+ on my dads C5 vette.