When you see the sole shots its clear how the shoes were actually unloading the back of the hoof rather than supporting it.
By contrast now he is able to begin to use the his frogs and heels properly and I expect to see him develop quite fast over the next few weeks.
Again the contrast is between a frog which is receiving stimulus and one which is shut down.
You can see from the position of the nail holes how the toe is shortening on this foot as well.
Its already loading better than in shoes with less stress on the toe and more engagement in the back of the foot.
Have a look at the difference in wall height between the lateral and medial walls. This should start to rebalance now that he is centrally loading his foot - it should be easier to see in a couple more weeks.
Merlin already had quite decent frogs, particularly considering he was in bar shoes, which gives us a great place to start from.
He's also a very inquisitive personality who is always on the go - a perfect quality in a horse who needs to grow new feet!