Depending on the answer to a very important question (to me), I'm pleased.
There is lots of snark in the comments (I realize that is a shocking reveal!) - but I for one am glad. True, major apps such as Instagram will benefit (and I absolutely agree there is little excuse for a well established app such as Instagram failing to support a truly native iPad app, but I digress...) - but what I am happiest about is games. I've lost track of how many times I've acquired an acclaimed game, only to find that it only runs in portrait mode. I immediately delete, no matter how well received the game has been.
All of which brings up my question... what about native iPad apps which only run in portrait? Will they also benefit, can they be set to landscape? If the answer to that is "no", then it's less impressive (and yes, at least with some games, I have found there are so-called "native" iPad apps which are limited to portrait).