A few things I dislike:

-Backtracking

-Escort missions

-Time limits 

Excellent storyline
Perfect controls.
Great gameplay.
Impressive replay value.

Other players... the hole reason I play these games is so I don´t have to deal with other humans... (not really kidding  on this one... only some  games are fun with other players...)

the cost

Repetitive levels (I'm looking at you, Sonic Advance 2 and Heroes)
Pointless playable characters (*cough* Amy in Sonic Advance 1 *cough*)
Plots that ruins the game (MMBN4. Most of the entire plot was about tournaments, not really fun and it gets in the way so damn much, the game sucks. Ugh)

Doing jobs to earn money. That's why I still haven't finished No More Heroes, and that's also why I don't like Animal Crossing. I also hate waiting for games to load (that means you, SSBB).

Story scenes that not only interrupt the gameplay but feature, on average, the worst writing and acting this side of an afternoon soap opera.

That, and long loading times.

Yeah, all those things suck.

Time Limits

The length