1. The worst thing about it is that he claims that he won't be president for half the country. That is awful, regardless of your politics. He could have said his policies would help these people, that he had a better solution to problems caused by poverty, unemployment, etc. But he didn't. He said there's nothing he can do because they'll never take personal responsibility. He's not claiming he's looking out for their interests; he's writing them off as lost causes. Despicable.
2. People who say that his claims are inconvenient truths are delusional. SOME of the things he says are true, but it simply isn't true that the 47% of people who don't pay income tax are all and only the people who vote for Obama, obviously. OBVIOUSLY.
3. One overlooked problem I think is that Romney is conceding the Republican party is the party of the rich. He's basically conceding the stereotype - "if you make a lot of money, I need you to give it to me to fend off all the poor people who will vote for Obama." But that's a problem for the GOP now and will continue to be a problem in the future. You can't run as an elitist, exclusive party and expect to win many elections. (Romney might still win this one, though!)
4. If the problem is that people don't pay income tax, an obvious solution for a candidate running for president is to promise to raise income taxes on those who do not pay. Obviously, that is something Romney isn't doing, nor would he in any near possible world. It actually wouldn't be a terrible idea to do that to a reasonable extent. But it won't happen. Because the real agenda is not to have everybody pay their "fair share" in taxes, it's to kick poor people. People who complain about others not paying income tax, but who do not think the problem can be solved by raising their taxes or ending their tax credits (to reasonable degrees) are just looking for an excuse to bash the poor, pure and simple.