I purchased my 1-owner (carfacts) used car in July of 2009 with 175,000 miles already on it. I have loved everything about it. Depending on the terrain and wind, the mileage has ranged from 36-54mph, with the worst coming from driving into terrible winds and the best from driving with a breeze (have yet to drive with a strong wind). Car gets about 49mpg in town when driving with care. I have put 5,000 miles on it since purchasing and it's averaged 47mpg city/highway. Have had NO problems whatsoever to speak of, even with the high mileage. Have only replaced the oil/filter (once a year or every 10,000 miles). I would tell any and everybody that they would love a Honda Civic Hybrid!!
The mileage is obviously its greatest feature. The trunk space is also good sized for a compact car. Rear passengers have plenty of room. I also enjoy the instant mpg meter, which pretty much "teaches" you how to achieve the best miles per gallon. It's changed how I drive a vehicle.
I wish the car came with a moon roof option. Highway mileage is best driving at about 55-65 mph. Would be nice if you could get in the 45mpg range going 80mph on the interstate instead of about 35mph. That's more of "wishful thinking" than suggested improvements though.