It takes a few years to settle down to regular flowering. The flower heads are of the lace-cap type, not full flower heads like the usual mop-head hydrangeas. It is grown as much for its leaves and good autumn colour.
I have 2 climbing hydrangea on a south facing wall for a no. of years. Each year it is covered with loads of buds but the buds never mature into decent flower heads.
The climbing hydrangea is good on any wall, including north facing but does not need a south wall.