I still think LinkedIn is quite useful. Sure, there are some bad aspects, like clue-less recruiters, and charging job applicants to be "at the top of the list" when applying for a job.
However, the good parts still dominate for me: updated contact-list of my professional contacts, on-line resume, highly relevant job ads, and the occasional "good" recruiter. I just recently wrote a blog post about this: http://henrikwarne.com/2013/08/21/linkedin-good-or-bad/
In terms of the online resumes, what I like about LinkedIn are the recommendations. Not the "endorsements" which are a flawed and totally annoying concept, but the good old fashioned text recommendations.
It takes effort to recommend a colleague, to compose a couple of lines of text that represent what you think about him or his work. That's why they came up with those shitty endorsements. And when looking at profiles, these recommendations is what I search for.
Of course, the system is gamed a little, as these recommendations are often reciprocal (e.g. "give me a recommendation and I'll also give you one"). But on the other hand, when recommending somebody, your reputation is on the line, so for example I never recommended somebody whose work I didn't like.
So yes, it's useful as an online resume. But it's also annoying to get countless of notifications from clueless recruiters that didn't even bother to do keyword matching on your profile.
However, the good parts still dominate for me: updated contact-list of my professional contacts, on-line resume, highly relevant job ads, and the occasional "good" recruiter. I just recently wrote a blog post about this: http://henrikwarne.com/2013/08/21/linkedin-good-or-bad/