My mum took my 4 year old recently fo the second time. He loves it. Just to mention that if you go online to their website they have all inclusive tickets that are a few pounds more than the standard day tickets. Thy look worth i from what extras you seem to get.
They had the most amazing 'travelator' up one hill that the children wouldn't get off cos' they thought it was a brilliant ride.
We also sat open mouthed at the family who dragged their picnic up the steep hills in 4 large suitcases on wheels. My children looked at my average sized tupperware containing egg sarnies with great disappointment and tried to get adopted by the other family for an hour.
It's lovely but don't go in the winter like we did. We were there in Feb and as the site is so exposed, it was bloody freezing! On the plus side there were no queues. You'll be fine going now but it is VERY steep. Great for littlies, mine loved it despite the cold.