I rode it in July. It's free for bikes and has a separate entrance from the one used by cars. The cycle lane is about 1.5m wide and only separated from the road via a white line. There is a pedestrian lane to the right of the cycle lane which has a better disonnect from the cycle lane - solid wall as per rualexander's pic.
The overriding memory was that the uphill went on for a bit (loaded bike) and it was breezy at the top.
I didn't fear the traffic, but the majority of passing traffic was Dutch and Belgian holidaymakers and they gave me a wide berth and the occasional toot-toot as encouragement.