Without all the ballyhoo, media attention, and jet set hangers-on of the group's 1972 American Tour, the 1973 European Tour was seen as having less drama — the biggest pending issue was the resolution of Keith Richards and Anita Pallenberg's 25 June drugs and weapons bust, which hung over them until a 24 October £205 fine from the Great Marlborough Street Magistrates Court resolved it — while showcasing consistently good musicianship.
Songs like "Brown Sugar" and "Gimme Shelter" were well received and Billy Preston's organ and clavinet added a contemporary and funky edge to the "classic" Stones sound, although the tour's relatively conventional delineation between rhythm (primarily Richards) and lead guitar (primarily Taylor) parts were later criticised by Richards.
[1] By the time of the group's following Tour of the Americas '75, Ron Wood would be in the band and Richards' preferred (if mythological) interweaved approach would be restored.
As Brussels Affair (and some other names such as "Bedspring Symphony - A Box Lunch and Meat Whistle"), it has been a popular bootleg in superb stereo sound and is often considered a 'lost classic' of bigger importance than some of the official Stones' live albums.
Indeed, on 18 August, before the tour began, Jagger had been quoted, "The only thing I don't really enjoy about playing live is having to perform the old numbers, even though that's what a lotta people wanna hear us do."