Many of what people consider to be drawbacks of owning a sugar glider probably relate to natural behavior of sugar gliders and all of the elements of captive care. Certainly, their nocturnal behavior and nocturnal lifestyle is probably considered to be one of the biggest drawbacks of owning sugar gliders. They are most active at night. That is the time that they are awake, the time that they may be playing, exploring, eating and performing most of their normal social activities at the time that we're asleep. That being said, it is possible to spend time with your sugar glider during the day. However their preference is going to be to get back to sleep, get into their pouches or go back to their cage as soon as they can and would prefer to maintain and continue a nocturnal lifestyle.
There's also the consideration of whether having a large cage in your home is a drawback to owning them. As opposed to other pets that don't need to be caged, you're going to have to have the space and the room and have to be able to keep the cage clean and presentable enough so that it doesn't present a problem, doesn't create a source of odors, and isn't unappealing in the look of your home if it's placed in a main room, like a living room and which is certainly recommended for socialization.
There is a strong time commitment to having a sugar glider when you first adopt them. Socializing them, handling them, spending a lot of time getting them used to you and the home and the environment is definitely part of raising a well-adjusted sugar glider, but it requires a time commitment that many people don't have. Also, the commitment to feeding them properly can be a bit complicated and a little bit costly. The need to devote time every day to preparing fresh foods is a requirement. The need to keep insects and to go to the pet store frequently enough to buy insects to keep as part of their diet. Sugar glider commercial diets are not always readily available and many people have to rely on ordering these on the internet in order to acquire them, as most pet stores may not stock them as well. Sugar gliders as well generally are not very vocal, but there are times where in the middle of the night, when they are awake and alert, they may start vocalizing and it may create a little bit of noise, but for the most part, sugar gliders tend to be fairly quiet.
So overall, there aren't a lot of drawbacks to owning a sugar glider as long as you're prepared, educated, and aware of what it's going to take to properly care for them, provide and meet their nutritional requirements and also, understand what it's like to own and live with them.