Bungie Studios' Chris Butcher hates Halo 2. "I [frackin'] cannot play Halo 2 multiplayer," he laments in an interview with Edge, "I cannot do it."
Butcher's sentiments are, surprisingly, shared by many in the Bungie studios, who feel that Halo 2 did not have that four- to six-week period to polish the game like they did for the first outing. There's even dismay over the oft-maligned cliffhanger ending that Bungie staffer Frank O'Conner parallels to the ending of Thelma & Louise.
The obvious promise, if you hadn't already guessed, is that Halo 3 is going to outdo its previous titles, correct the mistakes of the past and save puppies.* This writer still prefers the original Halo over its sequel, so it'll be interesting to see if the third game can bring the game to its fresh-and-exciting roots.