Cnet-"A free Outlook add-on generates an alert whenever you're about to reply to all the recipients of a message; alternatively, you can hide the Reply All button or delay all the messages you send. Gmail users can undo the send if they catch the mistake within 30 seconds."
But you can still go back to the old layout if you prefer.
Overall, this looks like a decent UI update for people that use multiple Google services.
Spam runs rampant on Gmail, but you have options.
