I must say I was very glad to be completely unspoilered for this before I read it.
It took me a few pages to work out what was going on, but once I did I wondered why nobody else has ever tried the tight-third multiple narrative quite this way. It's a really different, gripping and intimate pattern of story-telling, giving a rounded presence, both inside and out, to each of the six characters. (Susan perhaps getting less of a fair shake.) It blew me away.
It's also obviously a response to Ulysses, where Joyce tried a similar trick, but from fewer points of view and covering a single day. In The Waves, which is about a sixth the length of Ulysses, less is more, and we get decades in the space of 170 pages.
I had always thought of Woolf as a young novelist. But one of the points that struck me from The Waves was its evocation of my own experience of getting a bit older and watching my friends getting old with me, usually at more or less the same rate. So I wasn't completely surprised to find that she was much the same age as I am, in her late forties, when this was published in 1931.
It's one of those books I shall return to again in a few years' time, but I'm very glad that I found it now.