That looks good. One improvement would be to get a padlock and run the cable through the seat, around the frame, and around a stationary object. Also, make sure that both front and rear locks go to independent stationary object.
Ideally, anybody who wanted your bike would need to cut three separate locks. Now, if you were to replace one of the U locks with a heavy duty chain, you complicate that job even more since they would require different tools. Bike thieves are less likely to carry tools to break more than one or two kinds of locks.