Yes, the EU Constitutional reform treaty is an important feature of Lisbon, because it is making sure that the EU is able to be effective. The EU as it is, is unable to get much done, because everything is done by agreement. It is more important that the EU have enough teeth in order to be able to get something done.
The Lisbon Treaty is an attempt to reform the governing documents of the European Union to make it a more democratic conglomeration of states. This democratization is a necessary step toward the continued legitimacy of the European Union because it seeks the approval of the citizens of member states which purport to be governed by the European Union.