HUD is perfect for the power users, adds a lot to productivity.
Here is the HUD demo - http://www.youtube.com/watch?v=w_WW-DHqR3c
HUD for power users - http://www.youtube.com/watch?v=ZK2lMCMsios
All of this stuff is faster with keyboard shortcuts, unless it's stuff that you only use very occasionally in which case there would be only a negligible benefit.
The algorithm is also based only on text matching (presumably levenshtein distance) so typing "exit" isn't helpful if the application happens to use the word "quit".
HUD would be incredible if it was as clever as Siri at NLP and could search every app installed on my system at once.
So I could say stuff like "Set an alarm for 10 minutes time" or "email richard"
Not seeing much in the software centre either.