This is basically the DREAM Act done by executive order, which is the reason he's waited until now to do it. If the House and Senate had passed the DREAM Act, as he's tried to make them do for his entire presidency, he wouldn't have need to do this.
I support the end result either way.....but isn't this still a slight problem? Congress doesn't pass what we'd like so we just do it by executive order?
I'd argue that the bigger problem is that a majority in Congress voted to pass the bill and the rules still prevented it from passing.