Simon Amstell, Theatre Royal Haymarket, London

At the end of a thoroughly enjoyable show, Simon Amstell reads out some of his past reviews, to good comic effect. One of them complains that the 27-year-old is not a "natural comedian". "How could I not be a natural comedian? I'm gay and I'm Jewish," he wails.

Nevertheless, irrespective of these credentials, this criticism has been echoed on a number of occasions. Tonight, Amstell goes some way to answering it.

Amstell's comic voice lies somewhere between the subtly sarcastic celebrity-baiting one that he used to such effect on Channel 4's Popworld, and neurotic nihilism. "Is there anything worse than being alive?" he asks us, weary of relationships, heartache and the apparent pointlessness of it all. Baring his soul, Amstell's central thrust is that life is an illusion – there's no such thing as personality and we are all one. Rather than taking the hippie line, for Amstell it means "I'm God".

The show, however, is far from the ego trip that Amstell virgins might expect, and some vulnerability is on display, such as when he admits that the teenagers in Skins, for which he wrote an episode, are much cooler than he was at their age.

The spindly comic admits that young people generally make him feel uncomfortable. When he meets a 17-year-old, he wonders: "How can an adult human have been born in 1990?" Yet his own adulthood, in comedy terms, started at 14, and has progressed in reverse, with TV exposure preceding a return to the stage. He has come out at the other end looking as fresh-faced as when he started.

Moreover, Amstell is still young enough for his mother to intervene in his career – or, at least, to help him finish a story about his grandparents from the stalls. Lent perhaps more poignancy by the presence of both his mother and father ("he's on his third wife, which is fine"), Amstell's Essex family background is nicely drawn, especially in a routine in which he imagines both of their voices providing his car's satellite navigation system, contrasting the impatient tone of his father with his mother's: "At the end of the roundabout, turn right, or whatever you want to do, my famous son."

There's little doubt that his mother's pride would have swelled further after tonight. The relative opulence of the Theatre Royal was a fitting venue for a set that was rich and intricate enough to please, but not so elaborate as to distract.