"and in the fire was what looked like four living creatures. In appearance their form was that of a man," NIV translation
In the center of the light were four living creatures.
It is believed that these same creatures guarded the way to the tree of life (Genesis 3) and they also appear in Revelation 4 around the throne of God in heaven.
"but each of them had four faces and four wings. Their legs were straight; their feet were like those of a calf and gleamed like burnished bronze. Under their wings on their four sides they had the hands of a man. All four of them had faces and wings, and their wings touched one another. Each one went straight ahead; they did not turn as they moved." NIV translation
I must admit that I don't have a clue about what these creatures look like as I find it hard to even picture what Ezekiel is saying.
All we really know for sure is that they are always with the presence of God at His throne.
"Their faces looked like this: Each of the four had the face of a man, and on the right side each had the face of a lion, and on the left the face of an ox; each also had the face of an eagle." NIV translation
The four sides of the creatures each had a different face. The face of a man was in the front and we remember, from Genesis chapter one, that man was created in the image of God. On the right side (the side of power) they have the face of a lion which is the king of the beasts. On the left side, was the face of an ox which represents a servant as an ox simply does the work that it is told to do. On the back side was the face of an eagle and we remember that, usually, when the Bible speaks of eagles it is talking about speed.
"Such were their faces. Their wings were spread out upward; each had two wings, one touching the wing of another creature on either side, and two wings covering its body." NIV translation
Each creature had four wings and two of them were pointed upward just as they were on the Ark of the Covenant (see Exodus 25). This ark was where God would meet with His high priest.