If I'm reading the RTT link for February correctly, thats a big change to times arriving into Cardiff for commuters.
Previous Arrivals: 07:34, 08:34, 09:34
New Arrivals: 06:59, 08:02, 09:01
Likewise with new departures from Cardiff being 16:02, 17:02, 18:02
Possibly not great if you work 8-4 or...