I love this picture. As a big fan of the contrast of heroine with villain pairings, it is right up my ally.
Both Powergirl and Doomsday look great! The detail is wonderful, from Doomsday's bones, to Powergirl's torn costume, to the embers of the fire in the air. I like how Doomsday is holding Powergirl aloft, with one of his large hands gripping the bottom and sides of both of Powergirl's beautiful breasts, and with his other he is grasping her sharply ass. I like the slight turn of her hips from her slender waist, with how Doomsday's hands are pulling her helplessly towards him.
The only improvement I think would be if the artist had made her boobs just a bit bigger. I am NOT saying that because I am one of those guys that wants to slap huge boobs on every drawing of fantasy women, but because I really like it when artists try to stay on-model when drawing erotic art of those characters. Powergirl does have large boobs as part of her character design, so it would be on-model to make them just a little bit bigger. They still look really nice here, though.
Overall, really wonderful job. Thanks are due to the artist and commissioner for creating this picture!
A picture such as this deserves a follow-up! Hopefully the artist will make another, showing Doomsday fully fucking and owning Powergirl.