Given these requirements, I think SOM did an excellent job - the building manages to simultaneously be reverent and purposeful. It's clean, modern, and evokes the Twin Towers without parroting them. True, it doesn't have the postmodern panache of the Shard or some rippling Gehry building-sculpture hybrid. But I for one don't admire such deviations from function. Insofar as the critic values postmodern features, that is a matter of taste, not objective civic merit.
Furthermore, I think it is incorrect to conflate its design with other, unfortunate circumstances surrounding its construction (delays, budget, security, politics). The broad strokes of the design have been in place since 2005 (with the admittedly unfortunate scuttling of plans for the base and antenna array).