You might have read my previous rant about the N9 Missing links. Here are some more....
The Nokia N9 is missing a HDMI slot unlike the premium phones like the N8 and the E7. Its not that people use HDMI port much but still is a nice feature.
The N9 also has a micro Sim slot instead of a normal Sim slot, though you can get the micro Sim from your Network Carrier, though it is not readily available at most places.
Another important thing is the lack of dedicated apps on the Ovi store. Nokia has to work on this area to match Apple's App store and Android app market.