[shinerb]

My 9900 was a very solid performer for me. It simply did what I needed it to and was first and foremost a device used for communication.

What, besides the track pad, will I lose if I purchase a Q10?

[Branta]

We don't know whether you will lose or gain. The device is not yet released, the software is not yet in final build as far as anyone knows, and the independent reviews have not started yet. For sure there are devices in the hands of beta testers, but those who know don't talk and those who talk don't know.

Being cynical, I could say "around $500 off contract".

[Taigatrommel]

As Branta said, it is hard to say as of now. What I can surely say, you'll lose some customization options, there is no built-in theme support. While you can still adjust the font size, you can't change the font type of the system.
The profile management of BB10 (nothing in the BB10.1 change log as of now) is waaay behind what we were used with legacy OS. While it is easier to use, many long-time Blackberry fans have been disappointed what BB10 is offering there.