Mostly sea-cliff climbing and mostly quartzite with a few very minor outlying shale outcrops and quarries. The main cliffs and Castell Helen are multipitch, tidal and serious of access and egress. The routes are awesome. Do them you must, with respect due for seasonal restrictions, nesting birds and the seriousness of the situations. If conditions are not suitable for the main cliff there are some very pleasant climbs on Holyhead Mountain. Some lovely little gems can be found further afield at, for instance, Rhoscolyn and Smurf Zawn.
Seconded it in the wet, bottom 5B pitch was wet and came off - goosed; used all energy getting through this in the wet which meant the top pitch was a battle but luckily dry by that point. Awesome route, just need more in the tank before leading it.
