Briefly, the whole work interfering with my posting life schtick:
Beppe singles out the issue that I find rather offputting from the start, the character of Dr. Aziz. The man is a skilled surgeon, better, we are explicitly told, than his English overlord. And yet when introduced, his character is rather childish and even buffoonish. I cringed at the description of his response to the Major's summons.
Adela, even as we dislike her, doesn't fair much better. Vaporish females are irritating to modern sensibilities. As Hamlet points out, we don't know and it doesn't matter what happened in the cave. However, it's annoying that crux of the book is an unattractive virgin's inability to cope with sensuality/sexuality, to the extent of hallucinating about it.
That said, and I'll have more to say further on, the most salient aspect of the book is the gorgeous prose. It's impossible to read this and not be swept away by the beauty of the descriptions and the nuances of character and conversation. Forster, however open-minded, was still a product of his times, and we see his limitations in the character of Fielding, who clearly is Forster. Tolerant and just and willing to take a stand, he still can't quite transcend his origins.