Everyone hates UI changes. Wait 6 months and it will be the new normal.
Yes it was the first time on load, but why did Gmail take 30 seconds to load before it was usable? Why did a website take as long to load as my entire OS? 32GB of RAM, 4+4 cores, what the hell is going on?
I just tested again, 34 seconds from hitting enter at "gmail.com" to getting a compose window loaded.
Gmail used to be lightening fast, an example of what an amazing HTML5 webapp could be. Now it is a joke.