These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Quentyn Quinn, Space Ranger
Marty Stu: The main character. He's unbeatable, all knowing, smarter and saner than anyone else, who is never, ever wrong, no matter what.
More accurately, he's better, smarter, and saner than the crew of the Star Ship Enterprise—- which is not so much lowering the bar as outright laying it on the floor.
Also he's not unbeatable, as the meeting with the assasin shows he's not a lux adept, that makes his ancestor was far more skilled than he is despite being the bottom of the class. It's not that he's unstoppable it's just that the standards have dropped.
Also unlike his ancestor, the main character had to go through a rigorous training program to become a ranger, and it's stated in the opening that rangers are essentially considered elite professionals: Best trained, best equipped, the cream of the crop of all the forces of the empire. They have to be in order to operate pretty much independently for extended periods of time in potentially hostile environments. They don't give a ranger badge to just any fool who applies. It helps if you consider the main character as the Sci Fi equivalent of Green Beret, Navy Seal, or a Spetsnaz.