The fact that it is over-planted makes me avoid it, too. But that doesn't mean it's a bad rose.
When I gardened in NJ - Zone 6b - Knock Out was the only rose whose frame pleased me. It grew into an ideally shaped hemispherical shrub. It was generous with its flowers. And in one case of three there was a lovely, subtle scent to them. While most hybrid tea roses have flowers of the 'right' form I have yet to find a hybrid tea rose that can please me half so much. In NJ hybrid tea roses died of fungal disease. Here they die of spring frost. Or of weak root systems. Or of drought. Or because they are just not very vigorous plants to begin with.
I think there might be a few David Austin roses that please me more than Knock Out did. A number of floribundas do, too. A few old garden roses. And maybe some of the Kordes introductions from Palatine Roses. I tend to believe Knock Out is vastly overused because people are somehow predisposed to like roses and they want them to succeed in their own gardens. For many gardeners in the NE and Plains states it's just about the only rose they've heard about that does.
My hope when I moved here was to succeed with enough other roses that I'd not have to resort to planting Knock Out. So far I have not planted one.
