A shame they had to kill off both Grenn and Pyp. Jon could have needed some more friends on the wall.
Ygritte's death didn't really to anything for me, to be honest. I must admit to loosing my interest in her this season.
I kind of wish they would have stuck closer to the book when it comes to certain things. I know it's more or less impossible, due to time and budget restraints, but it would have been nice to see a hundred giants, like in the book, or more than a handful of wildlings attacking at the same time.
Some things did not sit well with me at all. Climbing the wall in the middle of an attack was pretty dumb. If they were going to climb the wall, why not do it where there were no guards? Also, Jon holding a dead Ygritte in his arms as his brothers were still fighting around him seemed so out of place. There is a time and a place for everything.