They looked more or less like an ordinary goat, but stood upright like a human (similiar to Minotaurs). They were covered in fur, which ranged to a host of colours, from red to brown, and even white.
Because of their goat legs, they were able to leap and jump great distances and heights.
The Satyrs were said to be a wilder people than Fauns, but mentally speaking were the same as any other people (some good, some bad). There were many who fought in war when called upon. Some fought in the First Battle of Beruna for both Aslan and the White Witch. In that battle, a Satyr was seen battling a Cyclops.
In the Prince Caspian (film), a Satyr called Tyrus jumped up onto Miraz's balcony, attempting to slay him, but General Glozelle emerged from the king's door, and fired a crossbow, causing him to fall to a brutal end.
Satyrs were magnifcant creatures. At the Second Battle of Beruna, in the film, you can see Fauns, Minotaurs and Satyrs leaping at the army of Telmarines. Most Satyrs carried fewer weapons than a Minotaur, prefering bows and arrows, but some also carried scimitar-swords and halberds.
In the 2005 LWW Disney movie, they appear as anthromorphic goats given human stature. Their main weapons in the movie were sickle-swords and long halberds.
In the 2008 Prince Caspian Disney movie, Satyrs have become more goat-like, unlike the Satyrs in the first film that had slightly more human-like features.
In the 2010 Voyage of the Dawn Treader movie, a Satyr called Caprius is onboard Prince Caspian's ship, the Dawn Treader, beside the Minotaur Tavros. The Satyr is almost as large as the Minotaur, and has reddish fur, with ram-like horns.