Two-line version of this review: You MUST read this if you have any interest in ancient Icelandic literature, this saga is one of the best, and culminates many trends in saga and Norse religion. This edition is quite good, and has a fine introduction.
Grettir was indeed an enormous, strong man. His name means literally "Snake" in Icelandic. But "Passing Grettir" was the name of an ancient Icelandic circle game, in which the participants "palm off" (as we might say) a dried animal [...] on each other - what an entertainment. (This ancient game was still evidently being played relatively recently on the world stage, with that same part of Napoleon's anatomy.) So the word "snake" is also euphemistic, for "[...]," I think most people should perceive the structural similarities... This guy was the (literally) ultimate Icelandic bad boy, but he certainly had a heroic side, and a perceivable ethic. He was the last-gasp incarnation of the ancient Norse religion, and he lived up to it perhaps better than anyone. He was the longest-surviving person to be outlawed in ancient Iceland.
The saga has many fine episodes, a fair amount of poetry, and a lot of clues as to how Grettir fit into the ancient pre-Christian religion. He faced down some of Iceland's worst supernatural boogies. I have read about twenty sagas, and this is without doubt the most genuinely interesting story. He does not say so, nor does the author, but I think he we are supposed to perceive that he was an incarnation of a Norse god. There are many similarities between this saga and the tales of the Norse gods; also, he is probably the model for Paul Bunyan (Grettir died in a fight partly because he was weakened by a bunyan on his foot, and he was famous for once carrying a cow out of blizzard - that would be "Blue," PB's ox).
One of the handful of most important works of ancient Icelandic literature.