This review will be quick, since there is not much to say about this app.
I was given a free copy of it to review (but I feel like I should have been PAID for the time I wasted on this).

Control/Gameplay [1/5]
According to the developer, you can use this app to “trick your friends by making them think somebody is at the door”.

You choose between static images of a doorbell, knock, and door
knocker and when you press one, you hear the corresponding noise.

“Simply ring the doorbell or knock on the door with Ding Dong Ditch
and your iPhone or iPod touch will begin to make that sound! Then sit
back and laugh as people answer the door only to discover that they
have been pranked and there is nobody actually there!”

No one I tried this on was in the least bit fooled.

Graphics [3/5]
Not much to complain about here, decent, easily recognizable static images of a door bell, hand and door knocker.

Sound [2/5]
The three sound effects were crisp and recognizable when played through
my headphones, but when I switched over to the speaker on my iPod
touch, the doorbell and knocking were still not loud enough (even at
full volume). I know it supposed to be on the softer side, so it sounds
like its coming from the door, but these were barely audible with the
TV going. Perhaps in a quieter environment, the ‘trick’ might be more
successful.

Replayability [0/5]
I see myself getting NO replayability from this app. In fact, its already been deleted off my iPod.
There must be some audience for this app, since it has a fairly high review score on
itunes…its just not for me.

Final Verdict [1/5]
Perhaps my friends are just too smart, maybe its the app…either way its
just not worth the money. There are a lot of better apps to spend your
99 cents on, which have much more replay value than this (Flight
Control and Pocket God come to mind). I recommend saving your money and
buying something else. Better yet, go to a Fast Food restaurant and buy
something off the value menu. The amount of time it takes for that 99
cent cheeseburger to go from one end to the other will be more time
than you will spend using this app! If you are really in the mood for a Ding Dong Ditch, on the way home you could stop at a buddy’s house and perform a traditional DDD and burn off a few of the calories.

Official Site
Buy it now: Ding Dong Ditch