Agreed. I just miss a few things. No more green dialogue boxes for Hangout chats? I liked seeing and knowing the difference in SMS vs Hangouts at a quick glance. It's no biggie losing it, but I miss it.
I also think the icons don't deserve their own row. Takes up too much room. Imagine the Hangouts/SMS icon on the left, then a pop out type menu (similar to how they had it before) on the right to send pictures, etc. That'd be neater, I think. And more importantly, I could see more of my chat.
I also wish that they didn't screw up with the automerge. I have a group of SMS messages from the person in one thread and Hangouts messages in another. I, also, can't merge them myself.