Sisteron is a compact and approachable crag, consisting of a large but narrow fin of rock, with slabby, sunny routes on one side, and a few shady, steep routes on the other. The rock quality is excellent, though the slabby routes tend to have cleaner rock than the steep ones. As a destination, it's not extensive enough for a base, but makes a good alternative to Céüse if you're feeling like having an easy day and can't face the walk-in.
Sisteron has a small climbing shop which also offers shoe resoles. If you look hard, you will find it at 12 Rue du Grand Couvert - tourist information should be able to offer a map and directions as it's well hidden.