A couple fairly well balanced articles, one for each side. To me, both sides have a valid argument. Pick which one you think fits the data and your own view better.
For:
http://josephsmithspolygamy.org/plural-wives-overview/fanny-alger/
Against:
http://mit.irr.org/joseph-smith-and-fanny-alger
For me, if I’m trying to be objective (knowing how hard that is to actually do), I think the “sniff test” stinks. Smells like more of an affair to me, and even if it wasn’t, I have a hard time truly believing that if God wanted plural marriage this is how he would have his prophet introduce it. Something just doesn’t seem right.
And poor Emma. She doesn’t get enough attention in how devastating this must have been for her.