"A Severed Head" is the first and very likely the last novel by Iris Murdoch I'll read.It isn't by any means a disgrace, but it falls far short of the expectations raised by the hyped reputation of Ms. Murdoch.
Ms. Murdoch is clearly not a great writer. Just read a page of Jane Austen, Charles Dickens or Virginia Woolf to remind yourself what acuteness of insight, depth of vision and felicity of expression great artists can achieve.
Alas, "A severed head" is not even a good novel. The twists of the plot are ludicrous (at the end of the novel, almost all male-female love relationships will have happened or been revealed in the brisk course of a few weeks), the characters little more than the embodiment of a few adjectives each. The dialogue rings false : there is precious little differentiation of tone and speech, every one drops high-brow cultural references at regular intervals. The mirroring of the narrator's confusion with the London fog is the very heavy simile that Ms. Murdoch beats to death for 200 pages.
This novel has been seriously crafted by a well-read professor who is not a genuine artist. The gist of the issue is that Ms. Murdoch has a few intellectual points to make (on love and seeing, mainly); she constructs her novel to achieve them, but does so with little of the true powers of vision and of expression on which the art of writing and the joys of reading rest. Intellectual novels can be successful, of course, provided there is enough spirit and/or language mastery to go with the ideas - think Dostoïevsky or Proust.
If you want a beautiful example of novelistic art, you'd do much better with "The photograph" an exceptionally fine work by Penelope Lively on the same theme, without the weighty intellectual pretensions. If you want to read a great modern novel, "Disgrace" by JM Coetzee will show you the abyss between a well-meaning but rather limp attempt at literature by a serious don and greatly moving art.