If you look on the OS map, it looks merely 'lumpy'! To me, it looks a bit like Cornwall, in that there are not massive climbs, but there are some steep bits and lots of ups and downs. It looks nice.
I stayed near Harlech last year and was looking across at the peninsula and wondering what the cycling was like there.
If you fancy a real challenge, nip over to Harlech and see if you can get up the incredibly steep little lane that climbs up below the castle!
TBH - it isn't far to get to some big climbs inland in Snowdonia, so I would be tempted to venture out onto them while I was in the area.
Have fun!