Very. Now that a bunch of patents are all are down on the table Nokia can see Apple may be able to make it very difficult to do a smartphone, something I believe they thought was unlikely originally. Apple has already seen Nokia can try to make it very difficult to make a phone at all. For either company to be successful it will cost A LOT, probably more than licensing given the suit-countersuit.
It's all a dance done with lawyers as the instruments and if both sides can play a meaningful tune to the others ears, cross-licensing is the settlement of least risk.