At least, we can see there was a significant increase of "Gmail interface sucks" articles when the new UI came out. That has to represent some part of the users, to the least.
The problem is that the numbers don't matter in isolation. It's wrapped in two assumptions:
* That it's possible to make something that the vast majority of the population likes. Especially for something as complex and context dependent as email. No matter what Google does some section of the population won't like it.
* That it matters to Google (or any other company) that N% hate a product. I don't care if 75% of the world hates my product if the remaining 25% love it - and shovel money in my direction because of it.
