If you can find a reputable piercer to perform this they should tell you about the problems associated with the piercing, including eating, healing time, and the effects on the teeth.
You may appear unsymmetrical if you pierce only one side! As with all piercings, it will hurt, and probably bleed for a short time. Be sure to keep it clean and use an antibacterial, such as peroxide, to prevent the site from getting infected.
Cheek piercings are capable of causing slight nerve damage which can result in a dimple-like appearance. The jewelry used is typically a labret stud, which has a flat back and will be less likely to damage the teeth and gums.
Go for it. It is an uncommon but not unheard of to have dimple piercings. With all oral piercing you will have a learning curve relearning to eat, talk laugh and smile. You must also practice the BEST oral hygene. An infection in a muscular area isn't fun for anyone.