When the first-prize winner of this year's BP Portrait Award was announced, it caused quite a stir in the media. "Mature nude wins BP Portrait Award 2012"; "Naked 'Auntie' wins £25,000 art prize", screamed the broadsheets (yes, the broadsheets!). There's a curious fascination with nudity in art: it somehow makes an otherwise taboo subject accessible and perfectly acceptable. Consequently, I was not surprised to turn up at the National Portrait Gallery to find swarms of people heading in the direction of the BP Portrait Award exhibition. Going round the exhibition was frustrating, as it was incredibly slow-moving; as much as that allowed me to examine the works in detail, I would rather have taken in the art at my own pace. 

Two things struck me about this year's entries, the first of which is the relative youth of many of the artists. The First Prize winner, Aleah Chapin (USA), is only 26 years of age, yet her intimate, nude study of 'Auntie', from a series of paintings of women she has known all her life, reveals a mastery of various techniques, which she uses to paint a worn and weary body - translucent skin, cellulite, her torso showing the effects of gravity (as the euphemism goes) - and the warm, smiling face of a woman who is clearly at ease with herself. Ignacio Estudillo, winner of the Second Prize for a monochrome portrait of his grandfather, is only a year older than Chapin, and his approach, too, is creative, though I felt that apart from the face, his subject's body lacked the definition that might have pushed Estudillo to first place. Third Prize went to 35-year-old Alan Coulson for his realistic portrait of the tattooed, bearded and be-hatted Richie Culver. 

The number of photos and hyper-realistic portraits, with their incredible intricacy, also surprised me. David Eichenberg's portrait, Devan Atmys, for example, is of a young lady stood profile to the artist's view. Despite its small size, I had to get very close to the painting to see the minute individual brushstrokes. On a larger scale are Ivan Franco Fraga's Le (Salmacis Num. 3), a portrait of the artist's girlfriend, and Antonios Titakis's Silent Eyes, a monochrome painting of a friend. Individual brush strokes and stipples are easier to see, but there is a remarkable photographic gloss effect to their work.

I remain ambivalent about realism, especially when used in portraits. It provides a telling, warts-and-all depiction of the sitter and clearly takes a lot of skill, patience and exactitude to make it 'just so', but I do think that using more expressive styles, softer palettes and so on is more aesthetically pleasing. My personal favourites in the exhibition reflected this. Tim Benson's 92 years uses wide, unblended brush strokes to capture his grandmother, a dementia sufferer, at the end of her life. Benson "wanted to show her in an ambiguous light...she could just as easily be in a conversation as in a state of anxiety", and that is exactly what he has done. I also really liked Nathan Ford's miniature portrait of his son, Joachim, with its earthy, unfinished quality - as though it had come from an eroded fresco - and superb use of light. I think my First Prize would have gone to this year's Young Artist, 29-year-old Jamie Routley, and his triptych of paintings of Tony Lewis, a newspaper seller at Baron's Court Tube Station. Despite the criminal mugshot style of Routley's submission - a gruff-looking Lewis is twice depicted facing forward, and once profile - his painting reveals a certain tenderness in the sitter's expression.

It was good to see that the art of traditional portrait painting is not an entirely forgotten form. Miriam Escofet's portrait of John Godfrey CBE captures the former High Sheriff's eminence, as well as paying great attention to detail in painting his luxurious, velvet uniform; and Benjamin Sullivan's portrait of the former Head Porter of All Souls' College, Oxford is not dissimilar to the many portraits of former Heads of College that hang upon the walls of many an Oxbridge dining hall.

The BP Portrait Awards exhibition comprises a wide variety of styles and media, including oil on linen, oil on wooden boards, and egg tempera (the effect of which particularly suited artist Leo Holloway's delicate-looking sitter). Some of the portraits will delight; others may disappoint. Either way, on my visit I overheard much lively debate and discussion, and that itself made the visit all the more interesting.

BP Portrait Award 2012 , at National Portrait GalleryJulia Savage reviews the BP Portrait Award 2012 at the National Portrait Gallery.3