We're not in the business of judging games. It's all a matter of preference unless the rulebook can't even provide inspiration for games using better systems. Thankfully, this is seldom the case, so don't expect a treatise on what's supposedly good or bad. I'm only interested in what I care for and don't need others telling me what that should be, although I always appreciate informative reviews telling me what to expect.
So no, don't ask what a game can do for you; ask what you can do with a game, because ultimately, it's all about what you can use. I call it "the feeling", and it's always been a trustworthy gauge. Are you immediately filled with a million ideas for a campaign using System X? Do its rules enable a thousand ideas you never knew you had? Are you eager to put this new thing to use? These things tell the truth of it.
When I got my Holmes Basic for Christmas, 1980, I immediately mapped a dungeon and badgered my family into playing. Yes, this new thing was clearly doing something for yours truly, but that wasn't nearly the half of it. The rulebook inspired me with a million ideas I immediately wanted to try. D&D was an activity. It's whole value lay in my ability to use it for my own purposes. Gaming wasn't just a noun for me. It was a verb.
Ask not what a game can do for you. Ask what you can do with a game, because that's the sum total of its value, even if you only mine it for inspiration...
Maybe you find an intriguing system that needs house ruling. How is this a problem, especially when the result is an awesome system tailor made for you? And short of actually redeeming a system, what about a rulebook you can mine for ideas and inspiration that fundamentally changes an existing activity? In all of the above, the game's value lies in its ability to be used. And like food or sex, we immediately know when we want it...