You're welcome, High Lord Tolkien! I found it entertaining, because the Green Knight insists that Gawain owes it to him to let him take a sword-swing unopposed, which sounds like it will be quite fatal to Gawain, so there's suspense to see how Gawain can get out of this alive without breaking his vow.
Nevertheless, I sometimes found reading it a bit tedious at times, as JRRT uses some of the original Middle English words to preserve the alliteration of the poem, which sometimes required me to frequently flip back to the book's glossary his son Christopher provided to comprehend the story the poem is presenting.
Having said that, another point of interest for me in the poem is when Gawain sets out to fulfill his vow after the next Christmas and ends up staying at a castle where its lord has him play a game in which they give each other their daily gains for three days, and the castle's lord goes out with hunting parties each day while the lord's wife keeps trying to seduce Sir Gawain.
It's obviously a test of Gawain's virtue, and one gets the feeling that the lord of that castle has some way of staying informed as to what occurs in his castle, even when he is absent from it while hunting. Anyway, Gawain's host Sir Bertilak gets several deer, a boar, and a fox during three days of hunting, while Gawain gently rejects the sexual advances of Bertilak's wife, aside from accepting kisses on the cheeks from her.
But she finally gets Gawain to to break the rules of his game with his host by offering him something, a gold-threaded silk belt that she claims is enchanted, a silk band that could save his life in his coming encounter with the Green Knight.
'Do you refuse now this silk,' said the fair lady,
'because in itself it is poor? And so it appears.
See how small 'tis in size, and smaller in value!
But one who knew of the nature that is knit there within
would appraise it probably at a price far higher.
For whoever goes girdled with this green ribband
while he keeps it well clasped closely about him,
there is none so hardy under heaven that to hew him were able;
for he could not be killed by any cunning of hand.'
The knight [Gawain] then took note, and thought now in his heart,
'twould be a prize in that peril that was appointed to him.
When he gained the Green Chapel to get there his sentence,
if by some sleight he were not slain, 'twould be a sovereign device.
Then he bore with her rebuke, and debated not her words;
and she pressed on him the belt, and proffered it in earnest;
and he agreed, and she gave it very gladly indeed,
and prayed him for her sake to part with it never,
but on his honour hide it from her husband; and he then agreed
that no one ever should know, nay none in the world but they.
With earnest heart and mood
great thanks he oft did say.
She then the knight so good
a third time kissed that day.
It's understandable that Gawain would like some guarantee that he will survive his New Year's encounter with the Green Knight, considering that his vow requires that he hold still and let the Green Knight swing a sword at him once without offering defense, an arrangement that will likely leave Sir Gawain without his head. Just the same, by not telling Sir Bertilak about getting the silken belt that day, he is violating his promise to Bertilak his host. But I agree with JRRT that Gawain is too hard on himself for not mentioning the silken belt, considering he doesn't seem likely to survive his tryst with the Green Knight otherwise.
Anyway, I liked this poem better than I thought I would, and it has some interesting twists in its story.