You will need a car to get anywhere. It's not far at all to Erice which is definitely worth the visit - an old walled city with a big castle (bring a sweater as it's up high!). Great views if it's a clear day. The GPS did work, but it took us on a roundabout way to go. Do your homework and know the general direction of where you want to go so you can validate the GPS is sending you in the right direction.
The agriturismo itself is wonderful! You really can't go by reviews from 5 years ago. The amenities are modern (outlets, good showers, etc.). The bed wasn't the most comfortable but that was on par with most of the places we stayed in Sicily/Italy with hard beds. The hosts are wonderful people and there is great history with this agriturismo. Ask them to show you their "museaum". Also, we arranged for a cooking class while there and it was wonderful! The pool is really large and a great place to relax. High recommend this agriturismo!