I would concur with her husband Leonard; it is her greatest novel.
It contains her most passionate views on life, human nature, human experience, the effects of time passing, and death.
And the book is very metaphorical right through to the end; she uses poetry to plumb each of the above. The book cannot be read like a conventional plotted novel. It is all atmosphere, sensation, and epiphany. And yet, read on it own terms (six connected characters are ‘the waves’), it has much truth to impart on all of the above.