Indeed this feature is a must, I have my music organized by folders and everything, but I prefer the library mode over the folder one, so browsing is a pain in the $%%.
As I have stated before, there many ways to make the browsing faster, to be able to jump through letters would have my vote.
Not enough time playing with it, but so far so good, stable and faster (I have +6000 songs on it).
As the previous post reported, the "more than seven albums" bug is still present.
The X5 is getting closer to a truly great player.