Personally, what I mostly hate about GURPS is disadvantages. It exploits human psychology to make otherwise good RPers into concept-sacrificing munchkins. The suggested baseline is that you can get half the normal starting Character Point value back in defect points, which could put a high exceptional character (Secret Agent, Olympic athlete, world renowned Scientist) into low-superhero territory. It means a character who takes no disadvantages practically cannot compete with his neighbor who does.
Even if you rule that taking disadvantages grants no points, simply having a list of disadvantages for players to peruse as they're finishing up their concept with the hint of a suggestion that they should work a couple of them into their characters to 'round them out' or 'add depth' makes people receptive to adding flaws they think are interesting at the time, even if it has nothing to do with the character.
I've seen good, trusted players who entered Disadvantages chapters with "Ninja who works for the Government" and left with "One Armed, short sighted, Pig-ugly, Alcoholic Cyborg-Ninja whose every waking moment and thought is brainwashed into him by the Government, which if it found out that he was a Cyborg would have him executed immediately and who has a sick and dependent daughter whose medical bills have put him in debt."
If I ever run an RPG with a Disadvantages chapter where it lists potential defects in this way, no joke, I will physically rip it out of the book.
That said, I'd probably run GURPS with the disadvantages chapter torn out, as long as what I was playing was a highly lethal, medium-low power semirealistic fantasy game with low or no advancement.