Pennsylvania Dutch programs so popular that prospective students have to be turned away

That's according to an article here on the revival of Pennsylvania Dutch (Deitsch) and courses taught on the language in such places as Emmaus and Quakertown. The courses are next to free, costing only $25 for 14 weeks.

As is often the case, a good way to compare Deitsch with modern German is to take a look at the Our Father, as the Wikipedia page for the language shows. You can see that words ending in -er often become -ah, and also pf- will become p- as with many regional varieties of German.

	Writing system 1 (English-based)		Modern German (close translation)	Modern German (standard wording)
	Unsah Faddah im Himmel,		Unser Vater im Himmel,	Vater unser im Himmel,
	dei nohma loss heilich sei,		Deinen Namen lass heilig sein,	geheiligt werde dein Name,
	Dei Reich loss kumma.		Dein Reich lass kommen.	Dein Reich komme.
	Dei villa loss gedu sei,		Deinen Willen lass getan sein,	Dein Wille geschehe,
	uf di eaht vi im Himmel.		auf der Erde wie im Himmel.	wie im Himmel, so auf Erden.
	Unsah tayklich broht gebb uns heit,		Unser tägliches Brot gib uns heute,	Unser tägliches Brot gib uns heute,
	Un fagebb unsah shulda,		Und vergib unsere Schulden,	Und vergib uns unsere Schuld,
	vi miah dee fagevva vo uns shuldich sinn.		wie wir denen vergeben, die uns schuldig sind.	wie auch wir vergeben unseren Schuldigern.
	Un fiah uns naett in di fasuchung,		Und führe uns nicht in die Versuchung,	Und führe uns nicht in Versuchung,
	avvah hald uns fu'm eevila.		aber halte uns vom Üblen [fern].	sondern erlöse uns von dem Bösen.
	Fa dei is es Reich, di graft,		Für Dein ist das Reich, die Kraft	Denn Dein ist das Reich, und die Kraft
	un di hallichkeit in ayvichkeit.		und die Herrlichkeit in Ewigkeit.	und die Herrlichkeit in Ewigkeit.
	Amen.		Amen.	Amen.

Is Deitsch a good language to learn for those that live in the area but are actually more interested in learning standard German? Sure it is, if that's the only way you can find a place to immerse yourself in the language. If you happen to be from that part of Pennsylvania and want to learn German but don't have anywhere (or the money) to do so, then it makes sense to learn Deitsch. German speakers themselves nearly all speak another version of the language at home anyway. It all depends on one's learning style - if you need that immersive environment and the easiest way to do it is with Deitsch, then that's what you do.