The HUD is one the most significant UI changes to hit the Linux Desktop in recent years, and I see how a lot of people will find it useful. But it's probably also going to be one of the most controversial changes, perhaps even more than the introduction of Unity (which has many more precedents).
In particular, it will be difficult to get even the most adventurous users to use complicated apps like GIMP (which the screenshot shows) exclusively with the HUD. When there are hundreds of functionalities you could choose from and you don't remember the exact name, the traditional menu is much more discoverable. At the moment, HUD only complements the menu without replacing it altogether. But if the HUD is some day going to replace the menu, it will probably need to incorporate some of the features of the traditional menu on the way. I hope Canonical remains responsive to feedback during the transition period. Shuttleworth has an unfortunate tendency to go all Steve Jobs and insist that it's either his way or highway when it comes to UI decisions.
It's also going to be interesting to see how HUD works in touchscreen devices where using the keyboard can be a significant amount of hassle. You could rely on gestures to some extent, but not all actions you perform on a computer can be easily represented with intuitive gestures. So Ubuntu's UI may need to split up again into desktop and tablet editions, after all.
As for myself, I feel rather frustrated with these changes because I love my little plastic rodent. I really don't like taking my hand off the mouse to type something.
In his initial announcement of the HUD (http://www.markshuttleworth.com/archives/939) Shuttleworth clearly had the discoverability issue in mind; the vision he put forward was that, with the HUD in place, the menu's main function is now to discover functionality; therefore, design effort should now go into a good replacement for that particular aspect.
In particular, it will be difficult to get even the most adventurous users to use complicated apps like GIMP (which the screenshot shows) exclusively with the HUD. When there are hundreds of functionalities you could choose from and you don't remember the exact name, the traditional menu is much more discoverable. At the moment, HUD only complements the menu without replacing it altogether. But if the HUD is some day going to replace the menu, it will probably need to incorporate some of the features of the traditional menu on the way. I hope Canonical remains responsive to feedback during the transition period. Shuttleworth has an unfortunate tendency to go all Steve Jobs and insist that it's either his way or highway when it comes to UI decisions.
It's also going to be interesting to see how HUD works in touchscreen devices where using the keyboard can be a significant amount of hassle. You could rely on gestures to some extent, but not all actions you perform on a computer can be easily represented with intuitive gestures. So Ubuntu's UI may need to split up again into desktop and tablet editions, after all.
As for myself, I feel rather frustrated with these changes because I love my little plastic rodent. I really don't like taking my hand off the mouse to type something.