What I find especially weird when it comes to German is that we had a reformation of our spelling. Neue deutsche Rechtschreibung (new German spelling(?)) is new for a reason. Stuff got simplified and the rules we use nowadays are based on phonetics, as far as I understand it. The usage of "s", "ss" or "ß" doesn't change anymore just cause you use a verb in a different tense for example.

As far as languages go, German with the new spelling rules, is pretty logical.(if you ignore genders....)