First of all, only use the trial IF you have already decided on your LinkedIn strategy!
- The Inmail feature is overpriced
- The “Featured Applicant” feature does not work for SEO
- You can look at more people that viewed your profile – marginally useful
- You get more results from your people searches – can be very useful
Verdict: most people do not need a premium package, but it is worth trying for free for a month once you have mapped out your strategy.