As for substantial criticism of gmail's new UX, why rehash what has been already discussed over and over again here and everywhere? just google for 50+ well thought out blog posts and comments to those blog posts and google forum discussions.
I'm sorry if you are a googler and feel the need 'to circle the wagons' out of misplaced loyalty. Or if you fail to see that it is pertinent to mention the person responsible for the changes out of a perverse sense of 'white knighting'.
Now please downvote this to prove how intelligent you are.