Though some of the efforts made by this organization have caused a bit of strife in the past, due to differing opinions on how the issue of terrorism should be approached, I believe that it is one of the few large organizations that is actually taking serious action against the issue. That counts for many things.
The reason that the UN Committee on Counter Terrorism is not an effective tool against international terrorism is that it does not address most of the important issues concerning terrorism such as why is there terrorism in the first place? Why are some countries in constant danger of terrorist attacks while others have had very few if any terrorist attacks? Why has no one ever called a conference of those countries who are most prone to use terrorism and those countries who are most likely to be the targets of terrorism and see if there can be some mediation and agreement between the two. In other words a UN Committee to explore compromise on the issue of terrorism would be more effective.