Rowan big wool is a pure wool from the rowan range. It has been around for a number of years and Rowan regularly introduce new shades and discontinue others. The wool itself has a lovely soft feel to it which makes it lovely to wear in a cardi or the like. As a pure wool it is also great at trapping air for warmth and so makes a great scarf too.

There are a number of pattern books that support this yarn and a quick look on the Rowan website indicates that new patterns continue to be be developed. There are a wide range of patterns available from jumpers and cardis through to scarfs and bags. I've used it on a number of projects including an orange cardi, two lovely long winter scarfs and my very first successful attempt at a felted bag.
The wool itself has a lovely soft feel to it which makes it lovely to wear in a cardi or the like. As a pure wool it is also great at trapping air for warmth and so makes a great scarf too.
So pros and cons of this wool are:

Pros
It is incredible fast to knit. Big stitches means creating jumper takes little time at all.
It's flexible enough to create interesting stitch patterns which lend themselves well to scarfs and hats.
It felts really well and this combined with the fast knit time makes creating a bag an easy weekend project, even for a novice knitter.

Cons
The wool itself is not cheap. However it is no more expensive that other Rowan products and it is a quality yarn.
You need larger needles which few of us have in our normal needle collection.
For sewing up items, you will need a different yarn as the Big Wool for me was too thick

So would I recommend this wool? For scarfs and felted bags absolutely. For jumpers and cardis I'm on the fence. It is quick to knit up and creates a warm product but for me it is too chunky and makes the end product look just too homemade. That said, I just spotted a new pattern while writing the review which will be lovely to knit in these winter months