Having a LinkedIn Premium account is the only way to get full access to the complete LinkedIn experience. Only once you have this level of membership can you really see how restricted you are with just a free membership. As someone who has worked for years in the staffing industry, LinkedIn is an extremely powerful tool and network so that I could make connections with both potential candidates and potential customers.
By unlocking the InMail system which takes away much of the restrictions on reaching out to people outside of your immediate network, LinkedIn suddenly becomes almost twice as useful. There are also more sophisticated ways of searching and filtering your search results, which can both be amazing ways to better fine-tune your searches.
LinkedIn Premium also carries a rather premium price tag. That's to be expected considering the host of extras one gets when upgrading over lesser accounts levels. Plus, if you work in a profession where a tool such as this can be directly tied to ROI, it's a great investment. In recruiting terms, if only a small handful of filled jobs can be traced back to your use of LinkedIn Premium over the course of a year, the investment pays off in spades.
Absolutely worth checking out, but do bear in mind that the product does carry a rather substantial cost.
I have utilized LinkedIn both while working for a specialized staffing firm and as a corporate recruiter. I've found there to be substantial benefits in both roles. I'd say the biggest bonus is the number of people you can have access to who could match the requirements of your position who aren't necessarily actively on the job hunt. Being able to find and reach out to these passive candidates is very valuable.