First, unless and until you tell which knives from which particular line you're talking about we can't give you more than the most general information. Also, if you've been following this board, you're aware I consider your sharpening tools to an integral part of your knife set. Let's start with the range of knives generally, so we can locate Henckels and give them a grade: Lousy, Not very good, okay, pretty good, very good, excellent and ridiculously expensive.
Henckels (with an "s") makes a variety of lines of knives at several different quality levels. They range from not very good to excellent (Twin Cermax). Their better, forged knives -- which are probably the ones you're friends are crowing about -- are in the pretty good range. All of their lines which begin with the word "Twin" are forged and made in German ... with one exception. Twin Cermax are made in Japan at a dedicated factory Henckels owns and operates (in other words, they're not subcontracted). Twin Cermax are very much high-grade Japanese, western style knives. Don't ask. You can't afford one.
Henckels fits in with all of the other big "German" manufacturers ("German" in quotes because I'm including Lamson and Forschner/Victorinox which are actually American and Swiss respectively), using a particular set of steels for knife making. Great handles, extremely high quality workmanship and fit and finish, mediocre steel. The other big name German manufacturers are F. Dick, Wusthof, and Messermeister. With a very few exceptions their knives are more similar than different.
From a pure performance aspect there are several manufacturers who will give you more bang from the buck than Henckels. I'm hesitant to make any recommendation until I hear more about what you do, what you care about in a knife, how you plan to keep it (or them) sharp, which type(s) of knife you want (chef? boning? paring? bread? slicer?), and how much you want to spend.
Let me know,