Do you mean it does not get many flower buds or that each flower stays like that one?
There are two types of H. macrophylla. Mopheads and Lacecap. The former is the one where all the flowers open and the latter has a central area of flowers which stay white.

it stays as it is so it will never be in full bloom shame i will have to get one that will thank you Owdboggy for answering my question x :)

I posted photos of two of my hydrangeas earlier today - Preziosa and Bluebird. Preziosa is a mophead, and Bluebird is a lacecap, so you can see the effect of the two bushes

And, in the picture, I can see lots of bud still to come. Looks healthy enough

The two different types can look stunning in their own way, the mopheads big and blowsy and beautiful....
The lacecaps a more delicate flower but still stunning