You probably know this as the Morte Darthur, a slightly misleading title since what Malory essentially does is put almost every Arthur-related story written before 1450 into one big book. This includes a lot of Arthur not dying. It also includes a lot of jousts, tournaments, fights-to-the-death-oh-all-right-nearly-to-the-death-then, woman-stealing, pagan-hating and magic.
And if all that sounds repetitive, well, it kind of is. Some parts are worse than others. The "Book of Sir Tristram de Lyoness" is not to be touched unless you have a lot of patience and a deep and abiding interest in lists of Knights Who Get Killed. But there are parts that are lovely to read simply because you've read them before; like re-reading beloved fairytales whose ends are already known, whose words slip into exactly the right places in the story with a satisfying mental clunk.
Other parts are like new fairytales, stories of monsters and magic and marauding knights. You have to read them on their own terms, though: don't look for character development or psychological realism here, but for symbolism, stylised exchanges and chivalry.
If you're a big Arthurian, you probably want to read this. (Seriously, it has everything: the Sword in the Stone, Merlin, the Once and Future King, the Quest for the Holy Grail - every Arthur trope you're ever likely to come across.) Other than that, though, it may well annoy more than it entertains. Although it might work better read in small chunks over a longer period of time, as you might read a collection of fairy-tales.