It has come out really well.
Especially as you must have had to poke around with the brush a bit.

Bibbles is right about a little weathering.
Another way to add a bit more realism is to pick out the odd stone here and there with a thin brownish wash, so that the stonework has a few darker stones.
Also drybrush a very light grey on a few, so the tower looks less uniform in colour.
This is a good example...

It need not take long and will be worth the effort, I reckon.
