The designer releases the pattern in bits and pieces, one part leading to the next in logical order... but without telling you exactly what it is you are making. Sometimes the intrepid crafter will know they are making a shawl of certain dimensions, that will contain elements of lace or short row shaping. You will almost always know how much of what weight of yarn will be necessary before you begin. Sometimes you will be told that solids will work best, for example, or that yarn with a halo will obscure some of the stitches, so best to pick smooth yarn.
Then you wait for that first section, often info on doing a gauge swatch so that you can pick the best tools (needle or hook) for the task.
I have tried doing KALs in the past, although not mystery KAL. I usually get pulled away by health issues, or patterns of my own that want to be written.
On a whim I joined the Leethal Knits Mystery KAL a few weeks ago, and it is a blast! I have been knitting on it as a reward to myself for a long year of hard work designing.
My first reward was to learn a brand new technique for creating live stitches as you knit, rather than needing to pick up stitches along an edge later. I am also getting ideas for my own patterns, and stripes are going to show up in 2011, I just know it. Most of the knitting in each section is great for tv knitting or knitting in public. Easy enough to do, without being totally mindless.
My knit isn't exactly like the others (I somehow ended up with a wide band of gray along one side of the top textured bit) but it's all good. It is fascinating to look at other in-progress photos
HERE if you are a member of Ravelry (it is free to join).
Lee has made this pattern mutable. You have the freedom to knit (within some parameters) as long or not as you like. You can change the direction of the traveling ribs in the textured band at will, you can use whatever yarn and needle combo you find pleasing. You can choose to make it in one yarn, or several. (I chose 2, and striped them as in one of the examples) She has done a great job of giving enough information for WHATEVER yarn you use and decisions you made, without making the directions too complex.
I have to say this is my favorite knit of 2010. And I KNOW I will be making this pattern in variation for a long time to come (Watch out pals o'mine.... shawls may be headed your way in 2011).