A climbing stand also allows you to be attached to the tree from the time you leave the ground, plus they are much easier to move when hunting conditions change.
This is true, however, should the stand be faulty for any reason then down you go. Also, it is easier to be mobile with a climber. I much prefer climbers myself for that reason. Nevertheless, in the context of safety, ladder stands are safer due to the fact you can use the safety harness system of being attached to a rope while getting up and down the latter stand.