After reading the announcement I was filled with joy, seeing how he was so openly admitting his mistake, instead of doing nothing because of pride. It was great to see.
One thing however - although the message certainly spread fast to the whole world (I heard it here in Norway, almost every newspaper had an article about it) and it made people think about Jesus' return, it probably did more damage than good. People might think of His return for a bit while the media is covering it, but more and more it becomes a false alarm. "He's not coming. So many have said he is, but he isnt."
We can all make mistakes about what we believe God's will is. And it's so painful to say you're wrong if you are. And this was a public matter which reached the whole world, it was certainly an important case too. But the damage has been done, and he/Family Radio deserves a lot of credit for repenting from this.
EDIT: I just noticed in the other special announcement on the site that he felt God led him to those dates. He just doesnt know the meaning of them yet. Sounds abit like the excuse the Adventists made up in the start after Jesus didn't return on the date they believed in.
That is unfortunate. Although I can understand the want to keep some of his authority, like: "I have a connection with God I just misinterpreted Him", just plainly saying "I was wrong" and holding nothing back makes it so much better.
Let's take this example and think of ourselves - would we make excuses when we're mistaken like that?