We had a couple of days of business in Luton prior to flying out from the airport to Provence. That was the reason we chose to stay here, and from the brief stay I don't think there would be any other reason to.
It must be one of the ugliest town centres in the country, old, tired, dirty, terrible architecture, shuttered shops and an overall impression of being run down and poor. Even the open space next to the Arndale Centre was depressing.
What little traditional architecture there is around the town centre of the old times was attractive and lifted the depression a bit - St. Mary's Church is an example.