He also wrote some absolutely fantastic episodes: Midnight, The Waters of Mars, Gridlock, Turn Left.
Davies is a pretty great writer, and he knows how to makes something entertaining even if it isn't the best. When I'm watching the Slitheen episodes in Series 1, I'm never bored, even if the episodes are campy as hell. Compare that to some of those from Moffat's run like In the Forest of the Night, The Power of Three, and Journey to the Center of the TARDIS, which are snoozefests. The only episode like that in Davies' run was Fear Her, so he's got the one-up on Moffat in that category.