Lots of angry sentiment towards this company here. I understand it doesn't necessarily bring this demographic as much value since most here are probably happily employed and don't need it. There's plenty of others who count on a service like LinkedIn, which doesn't have a good comparison (e.g. Twitter to Facebook). Personally, I've found value in it from the potential clients I've received (I'm a contractor) and the…
In another use case I've also used LinkedIn to find service providers. Instead of relying on word of mouth I can vet someone from their work history, endorsements, and recommendations.
So yeah, they have bad practices, but they're not all bad. I do have to say that what they do provide of value is easily replicable and this is probably a great opportunity for anyone who wants to start something.