It's really too bad they are pulling Incognito. I know there is probably more to it then I am aware of. I personally prefer Incognito to all other themes including Linear. It's just so cleaner and goes with pretty much everything. I actually went from the liberty 1.5 rom with the Linear theme, to Rubix with Incognito and I have to say I don't think I'll be changing roms or themes anytime soon. It's too bad they gave up on Incognito/Invertnito...
Here is what I personally like in a theme (not that anyone really cares... just giving my two cents...)
-A Simplistic, clean, and uniform look
-Black, white, gray (maybe a very little hints of red, blue, green, orange, etc.)
-Flat colors no crazy gradients
- I like to feature my wallpapers and widgets. Color laden and cluttered themes limit what wallpapers and widgets look good. "less is way more"
-No themed icons (when the icons are themed I feel like I should only have the apps the themer chose to theme or my icon drawer looks weird...ADW themes work best if you want themed icons)
Themed apps: Dialer, contacts, gmail/email, messaging, google search... maybe the Android music app (I don't like to have to delete apps or wait for the themer in order to upgrade them)
-Themed lock screen: Clean monochrome and minimal
Themes I have tried and feel come close to my personal tastes: Incognito and Invertnito, Frost, Avalon, Mysterious Beast (still not a big fan of the gradients used in this theme, but it's still pretty clean)... Runners Up: Linear, Matte Blue, UD
Basically as simple and clean as you can get... Incognito and Invetnito was the closest to a perfect theme in my opinion... It seems like %80-90 of the themes out there for the X are to cluttered and have way to much going on with color, and gradients, and obtrusive icons... I know the themers out there who work super hard are probably thinking people like me just need to shut up and learn to do it my ourselves... and their probably right... until then I'll have to run an old outdated theme and pray some themer out there has my same tastes...