e most common complaint about them is their ride quality. From my experience however they aren't too bad. They "bounce" slightly more than other trains but it's not an issue most of the time. If you get a particularly bad section of track the bounce becomes very apparent though as you watch the rear carriage launch what looks like a few feet into the air.
A reputation acquired early in their lives when a greater proportion of their journeys were over jointed track. On continuous welded rail they’re ok