A few folks have had questions or comments so I'll put some notes here.
The pattern calls for DK yarn....It is entirely possible to get gauge with a light worsted. But a gauge swatch is your friend if you have doubts.
The tubular cast on - don't make yourself crazy if you can't get it. While I think it is fun to learn new cast ons, not everyone does. A long tail cast on or most other cast ons will work fine.
One person says she thinks the stitch count goes off (1 too many)after the increases. If this becomes a problem, just do one less increase - drop the one you made rather than rip back). There may be errata on the pattern writer's blog, check them out of you have doubts.
I didn't realize there was so much bobble hate out there, I have always thought they were kind of fun. If you abhor them, Lisa has decided to do a bobble free hat called Brambles Beret. Feel free to join her in it.
April's hat KAL will be much easier, I promise. And oh I have #4 16" circs back in stock......