The Bumbo chair appeared on my radar in the last 10 years. It seems to me that the manufacturer has solved a problem that does not truly exist. Get a good high chair, or use a well-designed booster seat that can sit on the floor. If your child has motor delays, this chair is going to prevent the use of the correct musculature to gain independent sitting. Whoops!
The Bumbo seems to appeal to parents who want their young infant to sit upright for meals or play as soon as possible. The company’s website does a great job of listing all the benefits of propping up a child who is unable to sit by himself. They are not helping you. They are selling you a product.
If you have a 4-6 month old child who is unable to sit by himself, then congratulations. You have a typically developing child. Make sure your child is spending time lying on his stomach reaching for toys and in your lap learning to balance. Use a high chair that allows you to angle the back to the point at which your child doesn’t fall too far to one side, and use it for short periods at meals and play. Meals at this age are fairly quick and most children want to be free to move.
If you have a 7-10 month old who is unable to sit and reach for toys by himself, then this chair will not assist your child. Using it frequently, instead of building the skills he needs, will probably slow his progress and certainly will not speed up development. It might make him happier if he is frustrated, and might temporarily minimize your concern that he is not developing on schedule. Your pediatrician can review his progress with you if you are concerned. If your child is not able to roll over, and struggles or avoids balancing on your lap at this age, then you may want to carefully review his development with your pediatrician. By this age, those skills should be well established.
All the discussions on the web fall into 2 camps. The first will be families that are certain that this device helped them feed and play with their children, and state that their children loved the chair. Then you have pediatric therapists who, without exception, warn that the position does not promote mature posture and limits the amount of time that a baby can spend in positions that build skills.
The device has been recalled because parents sat children in the Bumbo on tables and beds and children toppled off, injuring themselves. Sometimes severely. Falling out of this chair when it on the floor has been reported and skull fractures have been reported from that position as well. A belt and a warning pamphlet were provided with the last recall, and that action further

suggests that this chair is not better than a well-designed high chair. It is probably less safe than a good high chair, and suggests less supervision is needed. The opposite is true. Use the Bumbo with the knowledge that is is not solving a problem for your child, and may be creating one.