In a long-ago college class, a friend of mine objected to Howard's End. He had been taking a class on the literature of women--as the only male, brave soul--and did not believe in Forster's women. I had enjoyed the novel, and didn't know whether or not I believed in the women.
Ten years and two novels later, I was still not sure whether I believed in the women, but I did not care for Forster. I think that it was The Longest Journey that did it for me, and set me thinking about Howard's End and A Passage to India. In particular, it was the scene revelation of Ricky's half-brother's birth.
I dislike in Forster his treatment of marriage, as disproportionately solemn, in books where anything else whatever is treated lightly and skeptically. It is as if one were reading Voltaire to the sound of harpsichord music, when sudden an organ breaks into Mendelssohn and a dull clergyman is reading his sermon on the text "For marriage is an honorable estate." One infers quickly that the cleric is not married; nor has he, like Dupanloup, "heard confessions in the provinces"; he has an abstract and innocent notion of it.
Could you argue that this is hardly Forster's fault, that the laws prevented his writing about the relationships that truly interested him? Sure, and I will regret with you the novels that were lost. But I can only go on those I have read.
Secondarily, I think poorly of the whimsy. You see it in "The Celestial Omnibus" and in one of the stories that Ricky Elliot is said to have written. I don't know what got into the the writers of that period that they had to turn out such stuff. But Saki did, Kenneth Grahame did, and to judge by Max Beerbohm's "Hilary Maltby and Stephen Braxton", quite a few others did.