Even though Sean was born in Dublin, Sligo has been McSweeney's adopted home for many years, and he draws great inspiration from the beauty of its landscape. His work reveals a fascination with the changing nature of the light on the mountains, the sea and the boglands, and he seems most at home in the miniature world of brackish pools, the shoreline and wild flowers. He can be described as a semi abstract painter. He has been the recipient of many awards including The Oireachtas Award (1968), The George Campbell Travelling Award (1980), the Carroll Award, IELA (1987), winner of The Claremorris Open Exhibition (1987/1988) and in 1989 he was awarded Bonn An Oireachtas.

In addition to his many solo and group exhibitions in Ireland, Seán's work has been shown abroad in Scotland and Wales in 1971 in "The Celtic Triangle" and "The Delighted Eye Exhibition"; "A Sense of
Ireland", London, 1980; Cagnes-sur-Mer, France in 1985; Beverly Hills, California in 1986 and at the Bicentennial Celebrations (Australia) in 1988. There was a Major Retrospective of his work at the Galway Arts Festival in 1990 and the RHA Gallery, Dublin.