One thing that nagged at me for some reason was, why did the zombie-dragon have tattered wings? Just because its a zombie now? That doesn't make sense, after it's been in a few battles maybe, but I just get the feeling that they didn't think about it and gave it tattered wings for no reason.
Getting off that, 2 things would have improved the episode for me.
1) If Cersei had actually sent her soldiers North, but planned to ensure that more Northmen died than her soldiers by purposefully showing up late to certain battles or retreating and leaving them for the dead occasionally or just generally undermining their efforts whilst still fighting against the dead. All with Jamie complaining about it.
2) If Cersei had killed Jamie.
Getting off that, 2 things would have improved the episode for me.
1) If Cersei had actually sent her soldiers North, but planned to ensure that more Northmen died than her soldiers by purposefully showing up late to certain battles or retreating and leaving them for the dead occasionally or just generally undermining their efforts whilst still fighting against the dead. All with Jamie complaining about it.
2) If Cersei had killed Jamie.