He was a lot like Caesar: a character with great potential that ultimately ends up being wasted. Though, at least with Caesar, he has the excuse of likely having incomplete information about exactly why and how the historical Caesar basically fucked ancient Rome over and was responsible for its ultimate downfall, along with that of Classical civilization.
Ulysses? He's clearly well-read and intelligent, but he wastes so much time trying to be poetic that he just comes off as overly wordy and generally mouthy. He commits the greatest possible sin of a video game antagonist: he's boring. He speaks in this constant, dull, droning monotone that just puts you to sleep. Plus, his motivation is just weak. A butt-buddy of Caesar who tries to fuck off from the Legion, gets pissed that the Courier unknowingly craters his new home and, instead of doing something sensible, like hunting you down with a fucking shotgun, decides to go full Bond villain with an idiotic scheme that will only set the Wasteland even further back than it already is.
Of course, there's a theory floating around that Lonesome Road was, at least partially, the head writer giving a giant "fuck you" to the Fallout series' idea that people could actually, ya know, recover from the worst possible outcome for the human race imaginable barring total extinction. Overall, its just a dull DLC with some interesting weapons and that's it. The rest is just staid and boring.