I find that since so many of the Combat Feats require you to use a full-round action in melee round after round, that it just becomes WAY too easy for an enemy to break a combo you are building up. All the enemy has to do is move 10ft or somehow prevent you from being able to use a full-round action for a round.
If you really want to keep the combo mechanic in the game, my suggestion would be to make it so that you can at least use the melee feats as a standard action, so that you could still use a move action.