I have used it for distances of up to 6 miles each way to the put-in, up big hills and down. Kayak is very secure-I have a glass Valley Anas Acuta that is a heavy, heavy beast and it never budges from the trailer or moves around at all.
Better than the other bike trailers as this one comes apart and you have a simple cart if you just need the cart and not a trailer.
Well-designed. Pricey but worth it.