Far more than The Philosopher's Stone (but much less than The Goblet of Fire), The Chamber of Secrets definitely felt like a greatest hits of the core sequences from the book. Several key scenes were presented without any real explanation and the foreshadowing that held the first film together was almost entirely absent. Bit characters, such as Gilderoy Lockhart, feel overly like parodies of themselves but do maintain a sense of purpose as comic relief.
On the flip side, the world and (particularly) creature design go from strength-to-strength. The basilisk is wonderfully sinister, yet snake-like enough that the Parseltongue subplot stays meaningful and the various cameos, such as the Mandrakes, remain both grounded yet magical, helping the world feel much more consistent than it rightfully should. Fawkes has always irked me a little, but this time around felt a lot more logical – even if I feel that a phoenix should be more beautiful (and less deus ex machinima) than this portrayal!