You can drive up a small lane from Talybont on Usk that does a lot of the hard ascent for you, it also takes you to a parking spot with room for a few cars and a small stone bench and seats. The walk from here is short and sharp, and the summit is crowned by a small stone circle, neatly laid out.
Tor y Foel is a very distinctive hill, pointed and well separated from the ridgeway that it is on so it feels like a hill on its own. It offers great views of the larger Beacons as well as over open countryside and the Black Mountains and Sugar Loaf.
It is a very popular hill, I saw lots of families doing it as well as groups of walkers. Tor y Foel is skirted by the Beacons Way, Taff Trail and Usk Valley walk footpaths so maybe people divert off of these paths to take it in.
It is also easy to walk from Talybont on Usk, which has many good pubs making this a nice pre-meal walk to earn that pint.
A really good little walk in a really lovely part of the world, highly recommended.