Many games allow players to further customize their PC by adding in advantages and disadvantages. They go by many names. The titular ones from this post are the ones I've seen most often, but I've also seen: virtues & vices, merits & flaws, perks & flaws, boons & detriments, and so forth.
Variety is very rarely seen as a poor thing, but some players don't like it. There are numerous reasons. Some don't like having to "pay" for little quirks that help, others don't like the flaw stacking that sometimes happens as people gather points for power builds. In a few cases I've heard the problem is less with the idea of a Perk and Flaw, but more the execution therein.
Where do you fall on the spectrum? Do you like them? Dislike them? And what game do you think does the best job of incorporating them into the game?
For execution, I think the FATE derivative games often do the best job. The reason for this is because you don't get character points at creation for most of your flaws, but rather points in session when they come up. This helps curb the tendency a lot of gamers have (and, tactically, rightly so) of doing everything they can to mitigate their characters weaknesses if not avoid it all together, and encourages players to instead embrace that weakness, let it make things worse for them, and in doing so get more power for other things.
What about you?