Guys,
if my lcd 2x16 display displays blocks on the first line, does that mean my display is f***cked up?
That happened to me and it was because it was wired incorrectly and was not initialized 
actually, blocks can also be a sign of contrast too high. Have you tried playing around with that? And are we talking home-made LCD or a commercial shield? if home made, make sure you take pin 4 (RS) to GND.
A 2x16 LCD un-initialized only shows the top line blocked out.
If both lines are blocked out Its either contrast too high or your writing 0xFF to every location.
Cheers Ian