I liked the Westerlings-as-double-agents subplot. Also the "super competent Medieval surgeon who's really a high-born girl sticking it to mom and dad" irks the amateur medical historian in me. I'd rather have the lovely Ms. Chaplin playing Jeyne Westerling.
The Podrick scene was funny but really silly.
I did enjoy seeing Margaery Tyrell trying to win Joffrey by appealing to his cruelty. That was smart, and I don't recall it being the book.
Overall, the only thing I really hated was their skipping over the Battle of the Fist of the First Men. One of my favorite scenes in the book.
I think in a book wioth a dozen subplots per chapter the westering one is weak. You have to cut something.
From a narrative perspective they decided to make Robb a major character. In the book he isn't a POV character. Therefore you needed to show his relationship develop. You can't do that and use the Westerlings without a great deal of exposition or additional screen time and they are pressed for time.
Also the Dany subplot is very far removed from stuff happening in Westeros. Talia (??) creates another link in that she comes from there and can talk about growing up in a slaver city for example.
Battles are a problem. In the book they are mostly skipped and they have huge costs to do for real. I guess they need to weigh up showing a battle verus doing it off screen.
Personally I would have shown the Battle on the Fist from Sam's perspective with some clever cutting and use of snow effects they could I think of pulled it off without having to run a full scale battle. Sam is involved then the Commander tells him to get to the ravens and he runs off through the snow to the sound of combat... I think they could have worked it and it would have been a good hard entry into season 3 but ... I know fuck all about making a TV show so ....