Handwriting is one of those things that seems like it should be easy on the iPad, but, in reality, it is fairly difficult. Unlike Apple's legendarily quirky handwriting recognition on the Newton or the Windows tablets of more recent vintage, the iPad is designed primarily for finger-based input, not for longhand wirting with a stylus.
Though it's not optimized for use with a capacitive pen, several companies including Vision Objects are enthusiastic about the iPad as a writing device and have developed apps that'll let you scrawl to your heart's content.
