I just picked up an Insight for my 2400 miles per month driving. My girl is driving my previous DD a 2008 Mazdaspeed3. Here are my impressions of the Insight (I've not driven a Prius. I can't get over the center dash)
Averaging about 47 in my half city / half highway commute. Getting about 44 on the interstates at around 70 mph.
Pretty comfortable ride. Doesn't handle half bad for what it is.
Easy as hell to drive, except when you want to accelerate. Down right scary slow acceleration unless you bury the pedal.
Has a lot of little lights and displays to keep you in the green and off the gas.
Build quality is better than my Lotus
, but not up to VW or even Accord standards.
Has F1 inspired KERS system
Got it at invoice