God that chase scene was horridGood morning blues said:Xen in Half-Life is a pretty good example of this.
I also thought that the level where you're chasing some guy through the Favelas was the low point in the otherwise thoroughly enjoyable single-player campaign of Modern Warfare 2, and that Grunt's side-quest in Mass Effect 2 was the single disappointing side-quest in a game where those were really the highlight.
It was more tedious than fun