• Keep the boot process fast.
• Keep the system modular and simple (not a billion scripts just to boot it up).
• Create a consistent GUI.
• Add meaningful UI hooks for non-graphical UIs presented by assistive devices.
• Make the API even more powerful.
• The Invisible Interface: Users don't want to use a computer; they want to get tasks done. The user interface should go out of its way to get out of the users way.
• You don't need to have an explosion in a paint factory to have a good looking User Interface. Windows XP, KDE 3 and even OS X have all given their UI's "My First Computer" makeovers; bright eye-candy and fancy-but-crappy features like "Inteligent" menus that re-order themselves all serve to distract the user. The UI can look good without being a Gumball machine!
• Minimize dependencies for vital system parts - if something screws up, the system should still boot. (e.g. if I get rid of the icon server, I can still use the system - but with ugly icons, of course).
• Dont re-invent the wheel! If we can do something by simply making an existing API more flexible, instead of creating a new API, then we should do that.
• See the big-picture. The kernel, appserver, desktop & applications all rely on each other. The correct place for a certain feature may be low down or high up the APIs; think about where the best place for it will be.
• In conclusion: "power through simplicity!" and "design it for the users."

(Pablo M: Just a question, if this is a Desktop OS, shouldn't it be more like "My first computer" and less the "I Love UNIX, do it with a CLI app"?)

(Vanders: Its not a black and white distinction :) Its perfectly possible to have a usable, simple, GUI that gets out of your way and lets you do some work without neglecting the user and forcing them to the command line. When I say "My First Computer", I'm refering to the look. Bright, flashy colours and big, wine-gum buttons are a distraction. I want a GUI that gets out of my way. I'm using a computer to get some work done, not look at the pretty colours! :D

Examples of a good User Interface include Windows NT 4 (Clean, simple design, gets out of your way, doesn't distract or try to be too clever or "helpful"), Amiga (Maybe a little too cluttered, but again, doesn't do anything silly) and Mac System 9 and down (Clean and simple, gets the job done). Examples of a bad UI are Windows XP (Argh! The colours hurt my brain! What the heck is *that* button supposed to do? Where did my menu items go?!?), MacOS X (I feel sea-sick. Whats the difference between those three coloured buttons on the window again?) and pretty much any version of KDE (1.x : Ugly, 2.x : Nearly there, but uh, theres stuff *everywhere* 3.x : Ohh, pretty! Whats it supposed to do again? All 3: It doesn't do that. Here, use the command line...)

Rick: I kind of disagree and agree with you Vanders. The interface can look good without getting in the way. For example: BeOS, it is graphically good looking, but is easy to navigate. I think that if we spend a lot of sweet, tears and time we can make the gui goodlooking and usable.

Vanders: I think the fundemental issue is that a GUI can be "Good Looking" *as well as* "Functional" :) E.g. KDE can be good looking, but it isn't actually functionally well designed.

Eike: Why not? The application "konsole" is the best I've ever seen. It's a bit too bloated, of course. I like the clean desktop of Sy0.4.4 as seen from the screenshots.

tepples: What about people with disabilities?

This maybe be of interest

SCS: I don't agree with "The invisible interface" DesignGoal. Maybe "The balanced interface" would be more apt? Users don't want an interface that screams at them, but they don't want to be made to feel lost either. Once when I was in a car that was going through a narrow winding gorge with a cliff on one side, a sheer drop to a raging river on the other and trucks driving at high speed on both sides of the road, the windscreen did the extreme condensation thing and we couldn't see - because of the obscure layout of the dashboard, we couldn't figure out how to turn the de-mister on. It is true to say that say users want to use their applications, or just drive their car without the dashboard getting in their way, but there're reasons why things ought to not be invisible.