Excellent review! I have had my HTC Flyer for just over a week and concur with your impressions of this remarkable device. I especially like the inking, form factor and sharp screen. A feature not mentioned is the HTC Sync App, which is a free download (from the European HTC site) that I use to sync my Outlook contacts and calendar. Although I haven't tried these other uses yet, the fine manual says that it also syncs documents, photos, songs, bookmarks and allows installation of third-party apps (not downloaded from Android Market).
Two accessory purchases I have made are the Targus "Truss" Leather Case/Stand for the Blackberry Playbook, which fits the Flyer pretty well and has a place for the stylus and the stock Sprint 3.5" x 6" screen protector for the Samsung Galaxy Tab. It only covers the display area, but is anti-glare and works fine with both touch and inking (and may even make inking smoother).
This is my first Android device so I'm still learning about capabilities and uses. I look forward to hearing more about your experiences.