Steel frames have notoriously good weight-bearing capacity, but it's always a good idea to double-check. Most standard single person hammocks can hold up to 250 lbs, so if you're hoping to share evenings with your special someone or have children who'd enjoy sharing, getting a 2-person hammock is a solid bet.
It goes without saying that steel, by design and composition, can simply bear more weight than a wooden frame pound for pound. That is not to say that wooden frames are necessarily poor weight bearers, however, the more weight you want your hammock to bear, the thicker and longer your wooden frame will need to be.
This won't be a problem for people who intend to simply "set it and forget it", but for those of you with the occasional bouts of adverse weather, moving a heavy wooden hammock frame can be an issue.
In exchange for reduced weight-bearing capacity, wooden frames offer a more "natural" comfort than steel frames. Wooden frames can safely flex under your weight in ways that steel frame joints cannot necessarily imitate.