Halcon: This snake is good...
I don't see a context in which the snake is good, at least as a counterbalance to god. In some contexts, the snake is neutral (if it represents Eve's inner dialogue, for example). In some, the snake is evil (as defined in the NT). Since the outcome of its actions is negative, there isn't a good option, IMO. Except, perhaps, as a warning.
I think the focus on "who lied first" is a distraction (though it might make an interesting Abbott and Costello routine). Even as an allegorical tale, it implies that god withheld important understanding from mankind and left us to our own (uninformed) devices, then punished us for it. It reveals a part of Yahweh's nature that I think we can see throughout the Bible, but that makes for a very frightening character. He acts in a manner that is arbitrary and unpredictable. Since he cannot be held to a moral standard, he is capable of anything. And we are forced to accept this as a good thing.