Rab Discontinued the Cirrus in March 2015. Sad face.
The Rab Cirrus is very similar in both quality and materials to the Patagonia Houdini. Both are among our favorite lightweight wind jackets. The Patagonia Houdini edges just ahead because it packs a little smaller and the hood seals out wind better. That said, the Rab has two hand pockets where the Houdini has none. This makes the Rab a lot better for storing extra gloves and hat on a day hike. It also has a cool buckle to put away the hood. So while we like the Houdini a little better, both jackets are awesome. The Rab Cirrus is a little less expensive.
Compared to the Editors' Choice Arc'teryx Squamish, the Rab is lighter but the Squamish is more useful for a wider variety of activities. We prefer the Squamish, but if you are mainly getting this jacket for ultralight hiking and biking, the Rab might be the better call.