For those that really need to lose weight I think these drugs are likely hugely beneficial. Obesity has so many downsides and is a huge net drain on healthcare systems.

In terms of long term effects the only medical study I saw that concerned me was done on rats and showed a decrease specifically in the muscles of the heart. This was taking into account general weight loss and appetite suppression (which might more generally affect muscle mass). Not hugely concerning for the obese that might see massive benefits but for those who are already a healthy weight and taking it to get 6 pack abs it might be something to consider.