I save these books as a sorbet between main courses--the series is great reading as a way to cleanse your palate between more serious or hard-hitting fantasy or science fiction.
Don't expect any lofty language, but DO expect a few laughs and a wonderful romp.
Skeeve aspires to be a magician--not to learn arcane sorcery or become all powerful, but to become a better thief. He considers his master a bit impractical in his use of magic...if you are not profiting from it, what good is it? After conjuring a green-scaled demon, the old magician keels over dead, leaving Skeeve to deal with the demon himself.
The demon called Aahz, however, is merely a traveler from another "dimen"sion, called Perv. Do not dare under any circumstances call Aahz a Pervert. The denizens of Perv prefer "Pervect"; those who mis-speak tend to lose their lives.
Skeeve is from a backward dimension called Klah (residents are called Klahds, read "clods") where technology is back at the medieval level. Aahz has been everywhere and readers will enjoy many inside jokes from our own pop culture.
Another great feature of the books is the quote that begins each chapter, usually expounding on one of life's great truths. One of my favorites is from chapter 21: "One must deal openly and fairly with one's forces if maximum effectiveness is to be achieved." -- D. Vader