By Suzanne Choney and Suzanne Choney

Sophos Security polled more than 4,000 Facebook users about the new Timeline feature, rolling out now, and more than half said that Timeline "worries" them because of security issues.

"The response was (an) overwhelming negative" one, said Graham Cluley, Sophos' senior technology consultant. Granted, "the kind of people who participate in our polls might be more conscious of privacy and security-related issues than the average man in the street." But it is an indicator of the unease around Facebook's most noticeable change in years, and about the kind of information it will serve up more visibly than ever before, such as your comments and photos, organized by year.

With Timeline — which no one can escape — "Facebook is encouraging users to enter even more personal details about themselves and their life experiences, and making it simpler for others to view the information," Cluley writes on the Naked Security blog.

"But might this not also make it even easier for identity thieves to put together a profile about an individual, discover the name of their first pet, and so forth? That's all information which could be put to a nefarious use."

Cluley said when he tried out Timeline after it was unveiled last fall, "I found myself shocked by the realization of just how much I had shared on Facebook over the past few years" in the way of "status updates, photographs, groups I had joined and 'Like's I had made."

It's hard to tell how serious the poll-takers are, as one of the answers to "What do you think of the Facebook Timeline?" by nearly 33 percent was: "I don't know why I'm still on Facebook." Another 8.39 percent said they figured they'll "get used to" Timeline, and nearly 8 percent said they like the new feature.

Cluley doesn't think TImeline will "be the catalyst for many people to leave. After all, we've seen Facebook revamp its site in the past, watched its users grumble, and yet still the site grows in popularity." And, as he says, many of us who stay with Facebook would miss it — specifically our friends — if we left it.

"But, if nothing else, use this opportunity to re-evaluate what you share online, spring clean your Facebook account and online friend relationships, and ensure that you are only sharing what you want to share, with who you want to share it with," he advises.

Cluley personally went more hard-core than that because of Timeline. "Previously Facebook had managed to keep my history of interactions with it out of my sight, but now it was there for me to see. And combined with the challenge I felt in keeping up-to-speed on Facebook's morphing privacy settings I knew it was time to go."

He said he downloaded more than 48 MB of photos and status updates he'd had stored away on the social network — then deleted his account. (You can read his tale of why he left Facebook here).

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Suzanne Choney and Suzanne Choney