The new Circle line - confusing for passengers, more work for station staff, forcing passengers to change at Edgware Road (up and down stairs, not easy for people who are mobility impaired, with pushchairs and luggage). The critical position of Edgware Road means that problems there impact heavily on the whole of the sub-surface lines.
Monday was OK, everything ran smoothly. Tuesday, a points failure at Edgware Road saw the District suspended all day between High Street Kensington and Edgware Road, with a knock-on impact on the whole line becase the Wimblewares can't all reverse at High Street and keep their booked working.
Is this really a change for the better? It looks pretty shaky thus far.