@Khethil,
Yes the wizard and the glass is great!
Its a nice side track from the initial story. Its always been hard for me to really get into any kind of a romance story... though kings take was good! It provides lots of back story that helps explain why Roland is the way he is. Easily one of the best out of the books, though the next one; the Wolves of the calla, is an excellent rival. The entire story of wolves of the calla was inspired by an old western "the magnificent seven" and sets the stage for the last two books pretty well...
Defiantly keep reading on its worth completing.