I've always felt like I was slightly fighting against the Pen tool in most vector drawing apps, especially when drawing Bezier splines. The direct manipulation

I've always felt like I was slightly fighting against the Pen tool in most vector drawing apps, especially when drawing Bezier splines. The direct manipulation looks like a massive improvement, and would also be more intuitive with a touch or stylus interface. Secondly, this is one of the best examples I've seen of genuine UX and HCI research put into a tool that everyone else thought was "good enough".