CE is a maddening feat that really requires progression planning to make work for you. Right now I'm playing a 20 point buy fighter that uses CE with threatening defense trait, full plate, dodge, and focuses on flail group weapons (including exotic weapon prof meteor hammer) with greater trip and combat reflexes. With weapon mastery, and all the focus/specialization flail feats doing double duty for shield/flail and meteor hammer for reach, this character had annoyingly high ac\cmd and very high cmb for trips. Factor in the disruption factor of denying a foe a full attack action because he has to stand up after being tripped, and being extremely hard to hit on top of that, and you've got a pretty reliable shut down fighter that can hang around because he has really high ac/cmd. Now I'm building him towards taking improved dirty fighting and quick dirty fighting to make dirty fighting maneuvers as attacks of opportunity chained off of trips, which may not be high damage output, but is extremely debilitating for an enemy (plus hilarious for or party to watch). I think CE is useful, but you need to be all in on the defense track if you want it to work
