From The Old New Thing:
Some commenters deplored the inflectional complexity of the German language. I find the complexity reassuring rather than offputting, because it means that you always know where to find the functional parts of the sentence.
The lack of inflectional complexity in English is made up for by its much more complicated structural form. English word order is nuts:
"I rarely go."
"I don't go often."
"I don't usually go."
Why does the temporal adverb go in front of the verb in one case, but after it in another? And it comes in the middle of the verb in a third case!
(Okay, technically you can put the adverb in any of those places, but it sounds stilted or changes the meaning of the sentence subtly. Try explaining that to a student of English and they will merely shake their head in frustration.)
Or consider the placement of the verb particle in English (which corresponds to the German separable prefix):
"I picked it up."
"I picked up the ball."
"I picked the ball up."
but not "I picked up it."
Now put these two rules together and you find that seemingly minor changes to a sentence (changing one temporal adverb for another, replacing a noun with a pronoun) has a radical effect upon sentence structure.
"I rarely pick up the ball."
"I don't pick it up often."
The sentence structure goes from "subject-frequency-verb-particle-object" to "subject-verb-object-particle-frequency". How is anybody expected to learn this?
In German, the word order is predictable. All of these sentences would be structured as "subject-verb-object-frequency-prefix".
For added fun, add "carefully" to the sentence and watch everything moves around again: "I don't often pick it up carefully."
I find it ironic that when a Germanic language discards inflectional complexity (making it harder to see the relationship among the words in a sentence), it compounds the difficulty by adding greater structural complexity (making it even harder still to see the relationship among the words in a sentence).
Twain complained about all the exceptions. Actually I find that German is comparatively lacking in exceptions; the rules tend to be followed fairly uniformly. Twain complains about "parentheticals", but it is the parentheticals that make English so crazy. In German, the rule is very simple: "The adjective comes before the noun". Even if the adjective happens to be complicated. "The to-its-winter-home-flying goose."
Whereas in English, the rule is "The adjective comes before the noun, unless the adjective would sound better if it came after the noun." "The goose flying to its winter home" but "The slowly-flying goose". Try explaining that to your dad.
English, now that's where all the crazy exceptions hang out.
For example, the adverb can be moved to the front for emphasis:
"Sometimes I go."
"Usually I don't go."
but not: "Rarely I don't go."
but not: "Always I don't go."
"Rarely" is one of those exceptions that require inverted word order:
"Rarely do I go."
And "always" is an even weirder exception: You can't start a declarative sentence with it at all! (Though you can start imperatives with it. Go figure.)
Swedish used to be a more heavily inflected language, but it has been shedding its inflectional complexity over the centuries. (The number of genders reduced from three to two; special inflective forms for plurals have been removed; the dative case is now obsolete...) To compensate, Swedish (like English) has been making the verb forms and word order more complicated. The word "inte" ("not") goes immediately after the finite verb, except when it doesn't. And sometimes it changes to "ej" or "ikke" for reasons I have yet to determine.