While I ended up not liking "Cadmium" so much, I did want to say that I thought this was a pretty good overall issue. I very much liked (for various and sundry reasons):
"Why That Crazy Old Lady Goes Up the Mountain" by Michael Libling
"Thief of Shadows" by Fred Chappell
and Steven Popkes's chilling SF/H page-turner "The Crocodiles." That's three of the four novelettes.
For the most part I also enjoyed the other novelette, Aaron Schutz's "Dr. Death vs. The Vampire," until it hit me that the reader is meant to feel sympathy for, and root for, Dr. Death. When I looked at him I decided he was a scumbag protagonist and he was but the lesser of two evils (the other, of course, being the Vampire). Dr. Death is given to the reader as an "almost-superhero." As such, he can choose to use his "super power" or not, whereas the evil Vampire acts only according to his nature. Dr. Death has a choice, the Vampire does not.
If Dr. Death were to use his super power only to defeat Vampires, then he would be a true superhero, but he does not. Dr. Death chooses to—at his whim—kill people already dying of whatever disease (an old lady with cancer in the story). I have a problem with anyone deciding someone else should die—aside from the person themselves, or their family members. It's no one else's choice. But Dr. Death decides himself who he will kill prematurely and who he will not. Not a good guy, even though it is rationalized that he is merely easing their suffering and shortening it. Hmm. This brings to mind President Obama's answer during one of the Presidential debates where he sidesteps a direct answer to the question of whether or not his health care program would provide help to the elderly who might have only a few years to live. He said it would sometimes be better to "give grandma a pill" (to ease the pain) than to provide treatment. Maybe so, maybe not, but it whouldn't be the government's (or Obama's) choice to make. It should be the family and their doctor's decision—not the government's—or Dr. Death's. So I didn't care for the choice the author asked the reader to make here. We're asked to make the good guy someone with a super power he doesn't have to use, but does use, to kill whomever he desires. Not my kind of sympathetic protagonist. The rest of the story was Jim Dandy, but again, as in "Cadmium," I felt it unfair the reader was forced to root for an unlikable character (in this case a murderer in his own right). If Dr. Death wants to stick to offing Vampires exclusively, then there might be some dandy stories ahead for him, but otherwise I have no use for him.
Of the eight short stories (at least those I have something I can say quickly), I enjoyed Sladek's humorous Bradbury spoof, Hilary Goldstein's take on Snow White and the Seven Dwarves, Dale Bailey's touching "Silence," and Lokiko Hall's "The Gypsy's Boy."
Rachel Pollack's "Forever" was "okay" but for some reason didn't work for me quite as well as "The Gypsy's Boy." Both are similar in that they attempt to show what happens when immortals (the Pollack) or other sorts of ethereal beings (the Hall) choose to comport with human beings on our mortal plane. In each of these cases, these immortals/beings end up having the human emotions they must adopt prove their downfall. In the Pollack, Forever must choose between saving a mortal she has come to inhabit or losing her immortality (IIRC), and in the Hall, the wind spirit who comes to love the blind boy Bireli must choose between her own selfish desire to have Bireli's love or allow him back his sight. You get tangled up in human emotions and even the gods pay the price sometimes.
Robert Onopa's "The Atchison, Topeka, and Santa Fe" was okay as far as it went. It kept me turning the pages (though not as quickly as some of the others, as we've read about runaway AIs of various sorts before), but I wanted to stick around to see where he was going with it—what new wrinkle he might have to add to the canon of these stories. All was preceeding in fairly typical fashion, and I was hoping for some neato resolution, and then wham—just another trite cliche of a "shocker" ending which shouldn't have been a shock to anyone who has read, or seen on tv or the movies, this type of ending a hundred times before. The air went out of my balloon quickly at this un-shocker of a trite ending, and I felt disappointed. The ending killed this story for me, I'm afraid.
So I ended up liking (or really liking) 7 of the 12 stories, and all but one of the novelettes, on which more space must be gambled from the editor's pov. I suppose Popkes's "The Crocodiles" would count as my overall favorite of this issue, though I could read Fred Chappell stories all day (even though this particular "shadow" story, while good, wasn't his best in this series; I can't wait for more).
And in re "Cadmium" and "Dr. Death": no, not every character has to be noble or likable in a story. It depends on the circumstances and context of each story, a case by case basis, as it were. In the above pair of cases the characters just weren't my cup of tea for the reasons given. One character will take out on her infant her own problems, while the other character chooses to kill not just evil Vampires, but takes it upon himself to decide who (among the sick) shall live and who shall die.
Each reader's mileage, will, of course, vary, depending on their own personal moral priorities, and whether any character in these stories crossed any line, or not. But I find it fascinating to see what kind of protagonists we are asked to sympathize with, or even to cheer for in some stories (not just with F&SF, or these two stories).