I did a bit of research on that after a comment by Josh here on HN, basically when the first stage isn't pressurized by all of the propellant it is more like an empty beer can. (ok a really really tall beer can :-). Once it is on the barge it has the gas thrusters on top (you can see them in the video) which are well positioned to provide maximum torque to the rest of the structure, but they have limited amounts of reaction mass.
The next step would be some way to secure the booster, post landing, in a structurally supportive way, on the barge. I can't wait to see how they pull that off.
That would be interesting. I was thinking perhaps a set of explosive bolts on the landing legs which punched into the deck once it was stable.
I was also quite pleased that they had solid video of it coming into land with a drone that was hovering off barge. That was a brilliant move on SpaceX's part.
In the new field of vtoL rocketry, you want to have as much of the landing gear as possible on the pad and as little as possible on the rocket. An expensive array of mass produced "autograpples" embedded in the platform would be preferable over any solution that adds mass to the rocket.
The next step would be some way to secure the booster, post landing, in a structurally supportive way, on the barge. I can't wait to see how they pull that off.