Well, I was disappointed.
The animation was incredible. The level of sophistication that has been developed, even since the first Shrek film, is incredible. Hair that moves like hair, shadows changing shape on the ground, water looking like water. The quality was amazing.
Pity the same can't be said about the script.
Shrek the Third had some very funny moments, and was well enough written to make it enjoyable, but was not as good as the first or second films. There were a lot of characters, which didn't bother me too much, but no character development, which did. The moral point of the film was driven home with all the subtlety of the last spike (look, Canadian history reference!), and the ending was as much of an anti-climax as driving home alone after a date.
Between the tickets, the popcorn and the parking, I spent $50, to see that film, and it just didn't feel worth it.
But it did look fantastic.