Samuel L Jackson looks great, I dont see what you could improve on him. Bruce Willis could be a bit better, the face looks good but there seems to be something wrong with it, maybe because Jackson's face is more black and white and his (plus Travolta's face) is heavily in shades of grey.
Travolta's face on the other hand just makes me wonder what you were thinking about when you made it. Did you just go "Eh... Fuck it"? I cant really complain much about your skills, Samuel Jackson's face looks really good, its just that Travolta only looks worse when standing next to that lol.
Overall it looks good, could just use more work in that face.
PS: Never knew that Tarantino had "Jerome" in his name lol