The link is to a DailyKos discussion of the "letter." I put "letter" in quotes because I don't yet understand how it was "released." If you click on the link that takes you to Obama's website, where the letter is posted, it's actually posted on a blog on some obscure inner page of the website. I don't quite understand how that qualifies as an "open letter" that was "released." It looks more like a "secret communique" that the general electorate isn't meant to see. If that's the case, then it's nothing more than pandering and political cowardice. If, on the other hand, he plans to release this to a larger audience, or in a more public way, then that would be better.
On the other hand, while I'm still pissed about the Donnie McClurkin thing, if Obama means half of what he says in this letter, then he's got some damned good positions. Repealing DOMA and DADT would be huge steps forward.