Google is so sneaky. This prompt inside Gmail gives you three options. The two most visible options (number 1 is 'Try it now' and number 2 is 'Continue') basically mean 'Enable Gemini AI to write emails.' The third option cancels it which is hidden well. Google, you could do better than this. This is a perfect example of a dark pattern. For those who want AI to write basic emails can enable it but there is not need to do this kind of "shady" stuff.
A month ago, Gmail offered Gemini to me on my corporate account. I decided to try it. It was total garbage. I decided to disable it. Didn't found the option. A search explained why: there is no way to disable it once it has been enabled.
Gemini is the new Google+.
I have no doubt that some people will find Gemini in Gmail useful, as some people liked Google+.
And who knows? Maybe some update makes it really useful some day.
The point is users should be able to decide if they want to keep it or not. They shouldn't be conned or coerced to do so.
That's the real reason most of people really hated Google+. Whatever the service is, nobody likes being forced to it.