Based upon what I am used to having from using the N900 and N8-00 The N9 is missing the following:

• Laggy, confused Symbian OS - glad to see it go. The more I use my N8-00 the more I want to throw it in a river.
• HDMI port. Never knew I needed it until I got to use it.
• Expansion slot for data portability.
• Overclocking. And the whole openess situation that allows OCing. This has saved the N900
• Replaceable battery - this is important if I am away from home. The N900 was super because of this and the N8-00 was not. It's amazing how hard it is to find an outlet and time to recharge when you are traveling.

The N9 looks good to me anyway, despite these deficiencies, and the first is not a deficiency. I can see traveling with the N900 and the N9 being better than with the N8-00 and the N900.