Linkedin's Skills Endorsement is flawed. I love the idea, but the problem is that the way it suggests for others to endorse their connections is flawed. They only show you the top endorsed skill for one of your friend and invite you to endorse it, and what happens is that (99% of the time), you will just follow their suggestion, rather than selecting the skills your connection really has. In other words, the rich (skills) get richer, and the poor (skills) get poorer.
Another problem, is that I am doing a career shift at the moment, but because most of my connections so far either know me Network Security Engineer or Blogger, my top endorsements are Juniper, Social Media and Networks Security, followed by ones like Firewalls and Twitter. For sure it reflects my expertise, at least the past one, but I would love to see some balance there, and see more endorsements for skills like Python, Machine Learning, Information Retrieval, Data Science, Statistics and the other skills at the tail of my list. One way is form more connection in those new fields so they can reflect my true skills now, but back to the first problem, the Linkedin suggestion system will keep them buried and it will be harder for those skills to get promoted as I want.
Hope they change such suggestion system one day, so my profile reflects what I really am at the moment.