The good, the bad and the indifferent

Of this year's shortlisted Turner prize artists, one is very good, one good and two indifferent.

The weaker ones first. Fiona Banner has been making artworks that incorporate language for more than a decade.

Now she's turned to pornography. The largest work in her room is the giant billboard Arsewoman in Wonderland, which tells the story of a porno film. Lurid pink words are crammed steamily together. To some, these are studies of the ambiguous link between words and images. To others, they are merely second-rate.

Liam Gillick's show is a Perspex ceiling in bands of colour, which throws a gentle, muffled, amber light on to a small exhibition of drawings of some of his projects – signage for a market; a book-cover, etc. (This man, best known for his sculpture, is versatile).

And now for the better news. Keith Tyson is a drawer, painter and maker of absurd machines – the one in the centre of his gallery is of two withered plaster angels beneath glass. These are tenuously connected to a test-tube, and to a water butt that sprouts leaves and claws. On the walls is a series of quasi-technical drawings, often funny and brilliantly executed, bursting with scientific symbols, mathematical formulae and scribbly, megalomaniacal speculations on the nature of the universe. In Tyson, Blake shakes hands with Heath Robinson.

Catherine Yass's photographs are shot from dizzying heights and embody our fear and exhilaration about falling and flying. A film shot from a tower at Canary Wharf provides the raw material for three photographs, collectively entitled Descent. A camera, hand-held 800 feet up, is tilted to simulate falling. Photography merges into abstract painting – and it's breathtaking.