Facebook's $1 billion gobbling up of Instagram has sent disgruntled fans of the quirky photo-sharing app to the delete button.

Twitter and other online platforms buzzed Wednesday with depictions of Facebook as a corporate monster trampling over a defenseless community of creative, free-spirited types.

"Guess it's time to delete my instagram app before Facebook ruins it," Twitter user Charlie Robinson griped.

In another tweet, Jay El Nino Garcia moaned: "Nice facebook just bought instagram. Another thing to delete."

According to analysts at Crimson Hexagon, which studies social media content, just 12 percent of 201,000 relevant Twitter mentions of the takeover were positive. Ten percent registered "disgust" with Facebook and another 10 percent promised to quit Instagram.

Why the outcry?

Facebook is wildly popular and has the same basic mission as Instagram -- encouraging people to build virtual networks on which to share their lives.

But for Instagram's 30 million users, the cult-status app has a very different identity to the mass market Facebook.

Unlike Facebook, there is no advertising, and certainly no selling of users' personal details to advertisers. It's single-minded, pure.

Sure, the main point is to share snaps, which can be made to look cool with filters, but Instagram's mobile-to-mobile traffic is seen as safe from the privacy problems said to plague Facebook's advertiser-friendly pages.

"Its ability to let its users delicately toe the line between public and private gave us a little breathing room from the all-pervasiveness of Facebook, and to see it whisked away feels like a tangible loss," wrote Jenna Wortham on The New York Times tech blog.

"The sale of Instagram brings a harsh reality into focus, the realization that the secret rooms or private spaces online where we can share, chit-chat and hang out with our friends are fading. The few safe havens that do exist are quickly being encroached upon or are next on the shopping list for a company like Google, Apple or Facebook."

New York magazine compared Facebook to an alien spaceship and said that for "some users, this looks like a sellout. And that's because it is."

Facebook founder Mark Zuckerberg went out of his way to reassure Instagram purists that they needn't get their hands dirty.

On his own Facebook page, Zuckerberg noted that users can maintain their Instagram photos off Facebook and also keep their Instagram followers separate.

"We need to be mindful about keeping and building on Instagram's strengths and features rather than just trying to integrate everything into Facebook," Zuckerberg said.

Zuckerberg may not be popular in all quarters of the global online world, but his announcement notched up over 140,600 "likes."

Among the many positive comments were "great decision" and "congrats!"

But even on Zuckerberg's virtual doorstep there were dissenters mourning the arrival of mega money into a cozy hipster world.

"A picture's worth a thousand words," wrote Peter RonPaul Kallman, crossing out "thousand words" and replacing them with: "billion dollars."