First of all, the skeleton is both resistant and immune to necrotic damage?
Monsters seem a little... boring. I've played 2e, 3e, and 4e, (besides many non-D&D games) and the latter is by far my favorite. Monsters had a lot of personality there. You could really tell a goblin, a kobold, a hobgoblin, and a gnoll apart by how they acted. Gaining advantage in certain situations is both bland and invisible to the players. I'll give them a spin and see how they work out in actual play but I think I'll miss the interesting and unique tricks that 4e monsters had.