I tried LinkedIn Pro as a try free for 30 days. This required a credit card as it will bill you if you forget to cancel. After a week or so, I was unimpressed and canceled. Or I thought I did. $150 later and three months of not seeing the recurring transaction on my credit card I realized that I had not clicked the right buttons to cancel. I felt cheated by deceptive UI design.
I've found a lot of LinkedIn's UI to be unintuitive even in areas where they have no motivation to confuse you, even when it comes to upgrading to Pro - my conclusion was incompetence rather than malice.
Side note: happy LinkedIn Pro user here, well worth the cost at least in my case :)