For the record, I agree with Mike on this: Obama's healthcare mailer wasn't quite as egregious as Hillary's Reagan ad (in which she distorted his praise for the former president). But, even if the mailer wasn't literally dishonest, it was intellectually dishonest, since it overstates the downside of Hillary's mandate provision, something that may be needed to achieve universal coverage. Worse, the Obama mailer could be much more consequential than the Reagan ad, since it will almost certainly come back to haunt a Democrat who tries to enact healthcare reform (and that includes Obama, who, as many have pointed out, relies on a mandate to get children covered).
Substantive questions aside, I think it was also tactically dubious. Prior to this mailer, Obama hadn't quite fought to a draw among healthcare wonks--most thought the mandate was important. But most wonks also conceded the logic of Obama's mandate-skepticism--there are enforcement issues, potential affordability issues for a small subset of people, etc.--and generally praised his plan (which was, after all, very similar to Hillary's in other respects). Now that Obama's using the mandate as a cudgel against Hillary, he's provoking a backlash in the wonk community (see Jonathan Cohn here and Ezra Klein here. I await the scathing Paul Krugman column.) So the Obama campaign is on the verge of transforming the lack of a mandate from an understandable if regrettable policy difference to a serious liability among the people who follow this, which is never good.