Kolaghan makes for an excellent top-end creature for a Dragon or Monsters deck in Constructed. The ability to hurt opponents for playing creatures and planeswalkers in the late game seems very relevant, as well. You could make the argument that the effect being instants and sorceries would be better, but that seems like it would be a bit too good.
The greatest complaint about this card is that she's just not good at all in Commander. The losing 10 life is irrelevant in that format where every card that isn't a basic land is limited to one copy. Giving creatures haste isn't enough at all to make him playable there, so he's almost useless in the format, especially as a Commander. However, that loss of life ability should be relevant enough in Standard to make Kolaghan at least somewhat playable for some time. Beyond that, however, this Dragonlord may well be the worst of the cycle.