In the English language we are using here, capital letters are used for the first letter at the beginning of a sentence, personal names, the personal pronoun “I”, and for some other names (countries, months, days etc.). Most other words are written beginning with the lower case character. German and Luxemburgish are the only languages today that also use capital letters for substantives or personal forms of address like “you” (Du, Ihr) as well as its formal form (Sie). But is does not end here. Adjectives that are understood as nouns in the context of the sentence are also capitalized; for example in “The beauty in life – Das Schöne im Leben” the German word for “beauty” is written with a capital first letter. The complete rules of capitalization in the German language are quite difficult and hard to summarize. Many if not all German primary school students will agree with me on that subject. I will not even speak about people that have to learn German later in life.
At this point the question arises if the German rules of capitalization are merely a way of making an already difficult language even more difficult or if it has benefits, too. First of all, and that is the case for all languages using upper and lower case letters, capitalization requires two complete alphabets, one for capital letters and one for lower case ones. Secondly, nowadays most people type texts on their computers, tablets, or smartphones instead of writing them down by hand. Some may argue that the need to use the shift key to apply the rules of capitalization increases the time required to write something. Furthermore, the time spent on teaching those rules to students could be used otherwise on “more important” subjects. Others even say that the use of any capital letter produces an uneven pattern in texts and that one will have no problems in understanding a text in absence of capitalization. The whole use of upper case letters was nothing more than a habit. But what are the benefits? One of the most frequently mentioned reasons for capitalization I found while doing research for this Question of the Week was the increased understanding of sentences in German by using upper case letters for substantives. Is this true? I for myself must say that German texts written with substantives etc. using lower case letters look “strange” and I have problems to locate the “essential” words of the sentences, but this might just be the case because I am used to German capitalization. If it was essential to use capital letters to find the important words, would that mean that all non-German speakers/readers are slower in understanding texts? In fact an experiment with Dutch people showed that they show faster comprehension of a text written in Dutch using German rules of capitalization. Tracking of eye movement indicated that instant location of capitalized words i.e. the important structures of the sentences is the reason for that.
Unfortunately there are many pro and contra arguments so that I cannot give a final answer to the question in the end. Anyway, this discussion is on for many years now.
 http://www.berliner-zeitung.de/archiv/die-auch-fuer-das-deutsche-neue-grossschreibung-war-ein-produkt-demonstrativer-gottesfurcht-im-barock-fing-das-schreibchaos-an,10810590,10202608.html (last access 01.12.2012)
 http://www.koebes.uni-koeln.de/guenther_nuenke.pdf (last access 01.12.2012).