These 20 Caprices are fun to play, but challenging, so they may be enjoyed for many years.  However none of the pieces are written in the extreme and the range has been kept reasonable.  I think that you will find that the Caprices lay well on the instrument.  care has been taken to write in rests to help with pacing & endurance.  The key signatures are all three flats, three sharps or fewer.  There is also a CD with the book for you to hear how Allen Vizzutti plays them.