Searching over all database tables/fields would allow
searching for some keyword you have in mind regardless
of where it appears.
Having to go through all the alphabet in a linear manner is
a good idea for user devices like an IR remote control but
is inefficient if you have a lot of keys in front of you
(keyboard).
Therefore it would be good if the "normal" keys like Play,
Pause, Select, Next could be reconfigured to special keys
like /,*,-,+ (or something like that) and the normal
character and digit keys could be used for searching.
If this is used, it could be an additional search key while
looking in some field like "artist", "album", "title". this
would allow using both types of devices (character keys
and up/down alphabet selection) and speed up searching
a lot.
Philipp