Recently I test drove an 2011 EX that has been on the local deal lot for a few months now; they have it listed at $21,500 w/a couple of dealer add-on's (floor mats, splash guards). Anyway, I thought it was a more enjoyable car to drive than the Prius (though no one would ever confuse it as "sporting" in nature). That said, here's some reasons why I have considered buying an Insight EX (need the EX to get simple things like C/C):
1) The EPA mpg estimates (40/43) seem to run on the low side; I've been reading a few of the Insight forums and gas mileage tracking websites for a few months now and it seems like people are getting closer to 45-48. Of course, it all depends on how you drive and people who are driving hybrids to maximize MPG probably aren't truly representative of hybrid owners as a whole. And to be fair to the Prius, a lot of owners on PriusChat get better gas mileage than their stated EPA numbers.
2) There are just too many Priuses (Prii?) out there. I'm not looking to buy a hybrid for the goofy "Look at me! I'm saving the World!" aspect...but I also don't want to buy a car that seems to be everywhere. The Insight is much more "rare" sighting around here.
3) Many of the QC issues that emerged w/the 2009/10 models seem to have been address in the 2011, though it may also be that this years' model hasn't revealed their problems yet. Again, I gather that info from reading owner's reports on "Insight Central" and elsewhere.
4) I own two Honda products (old motorcycle, neglected lawnmower) and I've been happy w/them. Sure, a car is not totally comparable to those, but I've owned a lot of other makes and I'd like to give Honda a try once.
That said, there are some drawbacks too:
1) The Prius still beats the Insight in mpg's.
2) The Prius' is a mid-size where as the Insight is a compact...and you can really tell that in the backseat.
3) IMO, the blind spots on the Insight are even worse than the Prius.
4) When comparing the options that I want from a Prius & Insight, the Prius II can be had for roughly the cost of an Insight EX.
Thus, I still haven't made up my mind yet; plus, due to the recent events in Japan, the scarcity of both vehicles means dealers aren't dickering on prices like they were. "Truecar" has been showing a steady rise in pricing for both cars, so I think I'll wait a bit longer for better dealer leverage.
M_C