One may as well begin with Helen's letters to her sister.
"A chance acquaintance beings together the prosperous bourgeois Wilcox family and the clever, cultured and idealistic Schlegel sisters. As clear-eyed Margaret develops a friendship with Mrs. Wilcox, the impetuous Helen brings into their midst a young bank clerk named Leonard Bast, who lives at the edge of poverty and ruin. When Mrs. Wilcox dies, her family discovers that she wants to leave her country home, Howard's End, to Margaret. Thus as Forster sets in motion a chain of events that will entangle three different families, he brilliantly portrays their aspirations to personal and social harmony."
I didn't like Howard's End as much as I was expecting to, which was kind of disappointing. There were a few good sections of it, but other parts were very dull and full of names. It's one of those novels, at least for me, that are very important scholarly, but aren't the most entertaining.
I enjoyed A Room With a View much more, although I can't exactly say why. I think the writing was better there, and I liked the story more too. In both, however, women are fascinated by a family they meet in foreign places (the Emersons and the Wilcoxes).
There were a lot of confusing parts in Howard's End too. I didn't understand what the big fuss was about in some parts as well. One part I did really like was the way that Beethoven's Fifth Symphony and its effect on people was described; it was around five pages of character study and description of the emotion caused by the piece. There were other mentions of music too that I enjoyed. Clearly Forster enjoyed music as much as I do.
Howard's End did improve as it went on, but I didn't end up finishing it. It was just too dull, and though the plot sounded interesting, the book got bogged down.
I didn't read the whole introduction, but in the beginning of it, David Lodge mentions that A Passage to India is widely considered to be Forster's finest novel. I might try reading that one.