I always find it easier and more scenic to approach from Abercastle. Take the left hand coastal footpath (When looking out to sea) and walk out with fantastic views through the gap in the cliffs towards Garn Fawr. It is signposted from the coastpath just after the little rocky bay and up the hill. This must be how it was meant to be approached from the water
Yes you can see both Ireland and the Llyn as well as Snowdonia and Cadair Idris, on some days all are visible. Garn Fawr dominates the area and surounding it are ancient possibly Iron age field systems. At it's base on the Pwll deri side opposite the Youth hostel in the farm yard there is an ancient corbelled hut some have suggested medieval but it seems much older reminiscent of similar structures on the West coast of Ireland, although probably utilised in the Medeival period.