LinkedIn has been of some value to me in terms of getting back in touch with former coworkers. But they've changed their authentication so that, instead of a login session lasting for the life of a browser process, it times out every day. So now I have to log in every single time I want to visit their site. It's ok with me that Amazon wants my password every time I place an order, but LinkedIn doesn't have my credit card numbers and so forth.
Am I going to delete my LinkedIn account? Not in the immediate future.
Am I going to bother to look at LinkedIn based on the "LinkedIn Network Updates" they send out every week or so? No--it's no longer worth my time.
Am I going to keep my profile up-to-date? Probably not.
Will I periodically visit LinkedIn when I think of a former colleague and wonder where he or she is? No, it's not worth the time.