I actually thought Tywin with Arya showed him to be more than just a cunning bastard, he actually had glimpses of affection/admiration for her. It let you see a better side of him while he was still being ruthless. Its always good to see a nice side to the bad guys.
And I thought it was done very well - bits turned into a battle between two people playing their own little game of thrones (well at least trying to steal info out of each other)
The book was a lot more drawn out and basically a lot more dull.
I think this was a big improvement, condensed a lot but also improved it.