There's a lot of good stuff in COTF. Some of the quest lines can be a tad bit grindy (hello, DH and BW!), but you never really feel it. There's a nice difficulty curve to the expansion that feels good, even two level cap increases later.
That being said, COTF will always be a tainted expansion for me, because of Gribble GobbleKnobber (KnobbleGobber? GobberKnobber? GobbleKnob? It's something vaguely sexual like that). I count myself lucky to have never ran Gribble GobKnobble's "easy xp" missions to grind XP. Dead Hills is one of the most bleak and depressing zones in the entire game, and while there's some nice aesthetics and design in certain areas, neither of those things are found in the Hallway of Endless Hell Gribble KnobGobble sends you to.
Most of my involvement with the COTF expansion has involved guiding all the poor, sorry, wretched, starving, lost souls who fall into the Gribble GobberKnobbel trap away from that cursed place and into the promised land of Literally Anywhere Else. You can see the hollowed out, thousand-yard stare in their eyes after a few million Gribble runs, and you can feel your heart wrench when the dead, monotone voices ask in general chat, "anyone lfg gribble?"
Fortunately, through persistent outreach programs, a lot of community support, and an abundance of love, we have largely eliminated Gribble KnobGob addictions in today's society. It took a lot of work, a lot of heartbreak, and a few untimely deaths, but it was all worth it. RIP Gribble KnobbleGobble.
Remember kids. Friends Don't Let Friend's Gribble.