The solutionLinkedIn's endorsement feature can a be used to get good feedback from people. It will tell you directly what you're bad, but it will tell you which are good at.
Here is how it works
If you want to know if people generally think you are good at something
Look at how many people endorse you for that skill. If you have lots of endorsements for other skills, but none for the the skill you are watching. Guess what? People are telling you you don't have it.
If you have a skill that you don't use often but you're wondering if you're any good at it
Make sure its on your profile. If you get a number of endorsements, people think you have that skill.
Maybe its time to hone that skill to perfection?
If you don't know if you have a skill, but want to test if you do
Go ahead and throw it up on your profile. People can always ignore it. If you get some endorsements there is some potential there. Maybe its time to start training.
I have almost 700 people in my network on LinkedIn. I'm getting a good sense of what people know me for. I also see where I need to do some personal marketing in order to let the world know I have a skill. The good news is that I am not surprised by what I'm being endorsed for.
Note: There are a few more steps you will want to do in order to fully run customer development on yourself. Customer development is not a term a coined. I discovered it via Steve Blank in his book The Four Steps to the Epiphany. I highly recommend you check it out.