The disadvantages are the time it takes to sterilize and prepare the bottles, and the cost of formula. I myself have breastfed, and bottlefed. Only the mother can decide what the right option is. Regardless of your choice the baby will need to be burped periodically between feedings. There is a couple ways to position your baby to burp.
Burping helps prevent spitting up and belly aches.
Please note burping does nt always prevent spitting up. Some spitting up is normal. At this age your babywill sleep the majority of the time. To do this try to make night-time feedings as quiet as possible, and as dim as possible. It is also important to lay your child on a firm mattress to avoid suffocation.