They're not really jets as you'd expect jets to operate. The parkflyer ones are what are called "ducted fans". The electric motor inside the thing spins a fan that pumps air through the duct(s).

The ones that're advertised for beginners usually do perform as begginer type models. Some are really not exactly good beginner models however.

Usually the easiest beginner models to learn on are highwing models with some dihedral. They will fly with stability that levels the plane when you let up on the controls. Gives you a break from flying of sorts. Gives you sort of a rest. And they're usually slower than most of the others.