Is the bumbo chair actually good? Worth buying?

Making babies sit up when they are not developmentally ready for it may cause more harm than good. I've also had friends who commented that their baby's thighs get stuck in the seat and they outgrow it very quickly. I wouldn't recommend a bumbo... http://articles.chicagotribune.com/2012-03-15/health/ct-met-bumbo-posture-20120315_1_physical-therapists-developmental-benefits-babies