Prepare yourselves for a shock: This time around, I'm not going to spend however-many paragraphs pissing and moaning about all the things I can't stand to see in transformation fiction. Instead, I'm going to spend however-many paragraphs praising That Which Is Good in transformation fiction!

Subtle in-jokes: An 'in-joke' is, of course, a gratuitous reference to something completely unrelated to the story. They aren't to everyone's taste, granted, but this is perhaps due to the fact that not all authors do them properly. In-jokes are best used as a garnish, not an entree; that is, failure to catch the in-joke should not render the story less enjoyable. Likewise, it's best for the author to not go out of his way to draw attention to his in-jokes; again, we're talking garnish, not entree.

Competent characters: All else being equal, I have more affection for a character who consistently opts for sensible courses of action than a character who consistently does stoopid things. I prefer characters who remember significant information to characters who get memory lapses at moments conveniently conductive to keeping the plot rolling. I'd rather read about a character who damned well earned his happy ending, than a character who got a happy ending in spite of all his mistakes along the way. I don't insist that characters be infallible, but when a character does mess things up, I want to be able to sympathize with his misfortune, rather than wonder what made him do something that idiotic.

Novice-friendliness: This point applies mostly to tales written for any of the various 'shared world' settings, but also to sequels. Given two stories, one of which painlessly feeds the reader all the data necessary to understand what the heck is going on, and the other of which was written under the presumption that every reader is of course intimately familiar with the entire corpus of stories previously written for that setting, I am likely to prefer the first story.

Characters with lives: I want to get to know the main character(s) in a story. I want to care about them, for good or ill! Which means that I like stories in which the author has gone to some trouble to ensure that his characters aren't just cardboard cutouts that exist solely for the purpose of experiencing whatever transformation(s) he felt like inflicting upon them.

Invisible authors: All fictional stories are the fabrication of one writer or another, of course -- but when it comes to fabrication, some writers are appreciably less obvious about it than others. And if a writer is the god of his story, I'd rather he be a a subtle god, one who works within the rules of his creation, than a god who imposes his will on his creation regardless of whether or not it makes any sense.

Exploration of consequences: Many stories involve powerful elements (magic, nanotechnology, etc) which the author introduced for one specific purpose, but are useful for many other purposes as well. I like it when a writer acknowledges those other purposes, works out how else those elements might affect the setting of his story.

Distinctive dialogue: Compared to storytellers whose medium is the spoken word rather than written text, authors are handicapped. Oral storytellers have a variety of 'tools' to work with -- gestures, tones of voice, facial expressions, and so on -- which simply aren't available to written storytellers. Writers have only words to work with, and I enjoy it when a writer has sufficient mastery of words that he can establish a character's personality simply by careful choice of words in dialogue.

Mechanisms for change: I give full credit to any writer who actually goes to the trouble of working out a plausible mechanism for the transformation(s) in his stories, as opposed to just saying "Don't bother me, kid -- it's magic, alright?" and letting it go at that.