Initial thoughts. I love the familiarity of this - it's not overly hard to grasp how to use it.
What I would really like to see:

• Automation of process movement via triggers. eg, if a booking comes in, I want it to engage a workflow sequence for me.
• Calendar integration, I don't want to have to check my emails for all notifications. I want to see a task notification most of the time.
• tagging. I'd like to be able to tag users instead of having to assign a task to a member. My developer has access to my website so I'd like to be able to tag them as necessary (and have it notify them by email), but I don't want to assign tasks to someone who isn't part of my business.