Yes I have, what type of experiences are you curious about? I have worked with him many times as he is of Celtic origin and so am I, so I connect more closely to Celtic gods/godesses. He is considered to be, by Irish and Scotish mythology, a Celtic version of the horned god. He can help you connect to animals, help you more effectively learn an animals behavior and mannuerisms to communicate with that animal and sympathize with its needs. He can teach you about earth, nature, animal, and faerie based magick including magick involving the 4 elements.
He is the very essence of earth. Depicted as a tall god half man half buck with a wardrobe made of leaves and twigs as he is one with nature. He is the ultimate go to for anything earth based. You can also ask him for help if doing outdoor rituals, especially in the forest or woods, and he will come to you and aid you in your working making it more potent. He will act as a translator for any animal, to help you understand what that animal is thinking as he understands the language of all earth bound creatures.
All that aside, the obvious stuff many people already know. Here is the fun part. Cernunnos, being a god who specializes in the affairs of the earth, he can help you tap into power that you never knew you had in order to manifest your earthly desires. He will show you things, little tips and tricks about your ascension, how to hold focus during meditation better, how to go into a deeper trance state as he believes the only way to connect with the earth and to your power is to become ONE with it. He can show you how to better do this. At first his exercises may seem to be unrelated to ascension, but keep evoking him, asking him to teach you, and after just a few short weeks you will notice a big difference and will be able to attribute it directly to him.
Many people don’t know this about him, they see him as just some forest dwelling god who oversees animals and trees. Not true. He can also help you with trees, if you are interested in tree of life magick, the Celtic tree wheel, etc. Not sure what term to use for that one as I have not looked into the Celtic tree wheel very far. But I have some books on it.