I hate to be asking, but... what has changed exactly? As one who has only ever used Gmail with a mail client, I'm not seeing any obvious differences since the

I hate to be asking, but... what has changed exactly? As one who has only ever used Gmail with a mail client, I'm not seeing any obvious differences since the last time I had to log into the web interface to set a few rules, except an unusually colorful Compose button - which might have been there for a while for all I know.