The spiked chain is good, but it suffers from Multiple Ability Dependency. To perform its basic role as a melee weapon, you need good Strength. To grant multiple AOOs from Combat Reflexes, you need good Dexterity. To gain more than a slight advantage at tripping and disarming your opponents, you need Improved Trip and Improved Disarm, which requires Combat Expertise, which means you need Intelligence 13.
The spiked chain gives an advantage in many areas. However, to be good in all these areas requires you to split your focus in feats and ability scores. With the right selection of feats, and assuming equal ability scores, a character can choose another weapon and be just as good or better in a specific area than the spiked chain user.
So, IMO, the spiked chain is not too good.