Also, keep in mind that the LU-21 isn't a real high-end uke. My first uke was an LU-21C (wifey still has it) and I've bought several LU-21 and LU-11 ukes for grandkids because once I set them up they are decent beginners ukes that don't break the bank.
But, they've all been rather quiet up the fretboard. By around the tenth fret you get more of a "tink" than a "twiiinng."
Also, they ship with Aquila strings which work well on them but I've found the Aquila strings to be very dead in humid weather. So, I'd definitely change strings but don't expect it to suddenly become super sustainy up the neck.
John