Well, _Jacob's Room_ is an explosion, the experimentation become technique. It's a book with a hole in its center, and that hole is the main character, Jacob Flanders.The book follows him from his childhood in Cornwall to a bit after his death during World War I (possibly, indeed, at Flanders Field). That death, like most of the significant events in Flanders's life, we never see. We see Jacob from many angles - the angles being the perceptions of other characters - but rarely do we get inside his own head. We also have scenes featuring those other characters in which Jacob is present only as an absence.
Except for that odd fact, this might be a classic novel of character. It is certainly a kind - an odd kind - of bildungsroman, for we do see Jacob's character formed, but (again) from every point of view but his own. Jacob grows up, goes to Cambridge, is moderately successful, and - just before the Great War breaks out - goes for a holiday in Paris and Greece. He has lovers. He has opinions, and argues for them. But, somehow, the reader never feels Jacob as a personality, a person (a "character").
In fact, I suspect that this is Woolf's whole point, suggesting that we can never really know another person, can only have impressions of them. It's a view with which I feel a certain amount of sympathy; at times those I am closest to are utter mysteries to me. But it is the opposite of the "novelistic" tradition in literature. It is, in short, one of the root points of "modernist" writing.
Plot? There hardly is one; rather than the flow of Jacob Flanders's life, we have a series of set pieces, individual gems that seem almost unrelated to each other, strung together only by the tenuous thread of his enigmatic self.