If roses thrive on neglect, why is the rosebush I planted all covered with little holes on the leaves and only had four flowers? I planted it this spring.

The soil is clay, I amended it with compost, it is in a partly shady area, and it's one of those roses with many petals (but I can't remember what it is) and it's a climber.

Is there something I should have done besides planting it and putting up a trellis? I do water it sometimes...