I found those extremely annoying, because if I recall correctly they often ran in long canyons. That was a real pain.Inland cliffs were present in CivBE and I always hoped Civ7 would have them since Civ6 skipped on them. I'm happy \o/
The cliffs I've seen so far in Civ7 seem much more limited in length. Terrain should be interesting, not frustrating.