In reply to Mark Kemball:
Yep, 'steady' VS is bang on for a climber who can jam and, crucially, use the crack for feet as well.
Most of the route is one big hold, so obviously it's going to feel a lot harder for someone who doesn't know how to use that hold. (Or is unlucky enough to have hands so big or so small that other people's perfect jams will feel 'off' sized.)
My tip for anyone doing a route on the Leaning Block for the first time is to have a quick recce of the downclimb off the back first. It's dead easy, but it can be a bit tricky to find from the top if you don't know it.