If this arc had been done on Deep Space 9 instead of TNG, Picard would have been a Borg for the entire season. At the very least, rescue him in Part II but take several months to deBorgify him.
And that would've sucked.
And what's this about "after Picard is rescued, there's no need to care anymore?" - huh?? What about stopping the Borg? Saving Earth? Sure, this stuff is guaranteed, but it's all about the "how".
I've heard many times that BOBW2 should've been better, but I really don't agree.
After Picard is rescued it just turns into low budget action movie schlock. Been there, done that......not much reason to care anymore.