Third time not as charming for ‘Shrek’

Two was company and three is indeed a crowd — at least as the summer of 2007 seems to be shaping up. In a season full of third installments of popular blockbuster series, today’s “Shrek the Third” follows in the unexceptional footsteps of its predecessor, “Spider-Man 3,” in more ways than one.

Both franchises actually improved from their boffo original episodes to their initial sequels. But in both cases, endearing familiar characters and high entertainment value don’t fully sustain a third time out as weak storylines take over.