Their legs were straight, and the soles of their feet were like the hooves of a calf, gleaming like polished bronze.
This seems added by way of explanation. Since Ezekiel has spoken of their human form, he adds that their feet were straight, although he calls them round or like those of a calf. I refer the straightness not to the feet only but also to the legs. It is therefore just as if he had said that these animals stood as men do.
These visions filled Ezekiel with exalted thoughts of the God he served, securing him for his work and arming him with power to speak what God would do. They struck terror into the secure sinners of Zion who mocked the prophets, showing them our God is a consuming fire; and they comforted the godly captives in Babylon, assuring them their God dwelt among them still.
AI summary
Commenting on Ezekiel 1:4-14
And their feet were straight feet,.... And they went straight forward, as in Eze 1:12; they made straight paths for their feet, and walked uprightly, according to the truth of the Gospel; did not go into crooked paths, or turn to the right hand, or the left; and having put their hand to the plough of the Gospel neither looked back, nor turned back.