They're quite good!
The one for The Empty Child
looks rather like the cover for The Dalek Invasion of Earth
I intend to write those novelisations myself one day...
"What have you been doing since you stole that antique TARDIS of yours, since you first landed on Skaro? Shouting 'Look at me!!! I'm not fighting a war!', while you battle the Daleks all the way through space and time."