Just read the flavor text. It perfectly describes entirely his function as a Dude in Doomtown. Steven Wiles is great in every deck with the exact purpose of getting something done on the cheap.
Use him to stall your opponent's win by a turn by bringing in 3 Influence for 1 ghostrock.
Use him as a studly cruise missile to assault, harass, and even intimidate your opponent. What does it matter if he's a casualty, he's going away the next day anyway..
Use him to steal control of a pivotal point of yours, or block an opponents deed from production. He doesn't get paid or discarded until after production.
Use him to combo off of deeds - The Town Hall turns him into a net cost of 1 (deeds production+lowered influence ammount) to keep him around. Or Telegraph Office yourself a little extra ghostrock.
Bring him back from discard with Hired Guns if you want to hear some groans from across the table.
All in all, a great dude to have on your side of Doomtown.