In Peeping Tom the quite hapless Barney Fugelman recounts his romantic and sexual successes and failures in the 1960s and early 1970s -- where even the apparent successes are tinged with failure. Fugelman doesn't do all that badly: for a while he seems to be quite happily married to Sharon, and then he finds second wife Camilla. But Jewish guilt and concerns, and far too much suspicion, weigh heavily on him and burden his relationships. The good times can not last.
It doesn't help, either, that Fugelman might be Thomas Hardy reincarnated. Revealed when he's under hypnosis, it's an idea that he doesn't want to take all too seriously. Unfortunately, wife Sharon is enthralled: she changes the name of her bookshop from "Zazie's dans le Metro" to "Eustacia's on the Heath", now specializing in all things Hardy. It actually turns out to be quite a success -- but it also means that Fugelman can't easily escape his supposed former self.
Fugelman resembles Hardy in many particulars, and his romantic life, in particular, seems to follow the same fairly bumpy course. As it turns out, Fugelman might also have a bit of another author in him: born a hundred years to the day after Hardy, he was born two hundred years to the day after the Marquis de Sade .....
Fugelman is in for some sexual experimentation, but he's also terribly jealous, which turns out not be a good combination. He has certain expectations, too, but reality disappoints. Wife Sharon, in particular, doesn't live up to his increasing expectations:

But it seemed that she just couldn't simulate ecstasy to save her life. She whimpered woefully; she moaned as if she were in the last stages of a difficult labour; she couldn't manage the most perfunctory paroxysm without banging her head. She didn't even know, although I showed her and showed her, how to lash the pillows with her hair.
"I might just as well be married to Vanessa Redgrave," I complained.

The escapades with Sharon -- and that is what the marriage seems to devolve into -- escalate, and the marriage comes to an end. He next turns to -- and winds up with -- Camilla, who runs the Alternative Centre for Thomas Hardy Studies. But things don't go much better for him.
Peeping Tom is a literary-sexual romp. Densely written, there are a fill of witty sentences and clever ideas. The book ambles a bit aimlessly, like Fugelman himself, but his misadventures are entertaining. From a performance of Peter Weiss' Marat/Sade to more about Hardy than most might care to know, it also plays the literary angle well.
Fugelman isn't terribly sympathetic, and quite a few of his actions (and reactions) questionable, which makes him a less than ideal central character. He's also of a different time: it's the late 60s and early 70s that are being spoofed here, and much of the behaviour and attitude of that time hasn't aged well. It does all seem quite a lot -- a very well-written and crafted lot -- about very little, an exercise that grew all out of proportion. It's quite heavy (in all respects) for what appears to have been meant to be a light book.