I will agree that it was the characters that made 'Aliens: Criminal Enterprise' interesting, and it's what kept me reading. However, with a "creature feature" franchise like, say, 'Aliens' or 'Predator', I think it can be a fine balance between compelling characters and getting to see the creatures getting some spotlight time as well. I'd say that's my only real complaint against Criminal Enterprise - the characters were awesome, but the Aliens took a real back seat until the end when all hell broke loose, and even then it was just sort of "Aliens steamroll the base, everyone dies".
Compare that to, say, 'Aliens: Rogue' where essentially the same thing happens, but instead you've got spotlights on both the main characters and minor characters dealing with it, as well as exactly what the Aliens are doing, as well as the "Rogue" Alien doing unique things no one has ever seen before. Or to the more recent Aliens novel, 'DNA War', where you've got memorable characters who think they're discovering new and interesting things about Alien biology and behavior. It makes the Aliens seem more important to the plot than just a looming, frenzied threat in the background.
Compare it to, say, the first two Alien movies. Everyone remembers the characters like Ash and Ripley, but they also can't forget the things the Alien did, either. or in 'Aliens', characters like Hudson are memorable and quotable, but everyone also remembers the first time they saw the Queen at the end of the movie, too.
I'm not saying Criminal Enterprise was bad; very far from it. I guess I was just expecting more "Alien participation" to balance out the cast of characters that inhabited the base.