I once made the joke that Grendel was the first beo-degradable monster in history...
When I gave this joke to an English professor, he used it in class, and promptly returned it to me.
Okay. I'll accept that. But, Beowulf deserves the kind of serious attention that would prompt people to want to make bad jokes about it (unimportant things are ignored; only important things are held up in jest).
Beowulf is an old poem--often considered the first in English. This is technically not true, for linguistic and other reasons (where the demarcations of English beginnings fall are debatable; also there is the fact that there are older poems, just not epic poems). An epic is a long, narrative poem, a literary form undervalued today, but which was probably the equivalent of a Cecil B. DeMille production in more ancient times. The Illiad, the Odyssey, the Aeneid, Gilgamesh--all these are epic poems. Generally, they recount heroic deeds, and most often were composed and intended as oral history. Beowulf consists of 3182 existing lines.
Scholars also disagree on the 'British heritage' of the poem, many believing it more likely to be an import from Anglo-Saxon European homelands than a composition original to the Britain. The tale does portray two leaders, Hrothgar, leader of the Danes, and Beowulf, leader of the Geats, a Swedish tribe. These are interconnected through generations of family intermarriages, and Beowulf because of this loyalty takes his men to help defend Hrothgar's home against the monster Grendel.
The tale of Beowulf involves heroism, sacrifice, loyalty, warfare, conflict and resolution--all the elements that go into a good action feature. It also has moral overtones (so it was meant to educate and inspire as well as entertain). It carries the strong message that a fighting man's allegiance to the overlord and to God should be absolute (something that is often instilled in soldiers of today). It is almost decidedly Klingon in the glorification of battle (in fact, I've often wondered if the Star Trek universe took a leaf out of this epic to create the Klingon idea)--Beowulf fights three battles (a holy trinity of battles, almost), dying gloriously in the final battle with a great dragon, after having lived an honourable and courageous life.
This story contains elements of both early Christianity and late paganism, however in some cases the Christian aspects may be later additions by monks who transcribed the manuscripts (monks were noted for doing that in many circumstances, including Biblical texts). The oldest existing manuscript dates from about the tenth century and is preserved in the British Museum.
This particular translation of Seamus Heaney (a 1995 Nobel laureate) is a beauty to behold. Opt for the dual language edition if possible, so that you may compare the Old English with Heaney's recreation -- his economy of language (often but not always found among Celtic poets) lends itself well to the simplicity and economy of the original Old English. Heaney does often maintain the alliterative flavour, but resorts to truer meanings rather than translation quirkiness. He also often has to recast the cadence of the verse, as Old English did a sort of four-step that modern words however simple often cannot emulate. Yet for all the criticism that may be levelled (and in Heaney's case, many fewer than most translations of Beowulf would have to bear), he was done perhaps the greatest service a translator can do to any work, particularly an ancient one -- he has breathed new life into the poetry so that the story and the language can live again.