First, the most difficult thing in my opinion is the pronunciation. The Norwegian alphabet has 3 extra letters from the English alphabet. First, there is the "å" which makes an "oh" sound as in "poke." Then there is the "æ" which (I think) makes an "ah" sound like in "Tom," not to be confused with the "a" which sounds like the "a" in "apple" or "ask." Finally there is the "ø" which makes an "uh" sound as in "up," but with a nice twinge of agony to it. This letter was the most fun to hear our professor teach us. She said it literally sounds like someone has punched you in the stomach. "Ugghhh."
If you still need help understanding these letters, here is a fun video that explains it better, and also takes a jab at the US:
And now on the the next thing about pronunciation: the Norwegians take there time when saying their words. With a word like "pen," you draw out the word and say "pehhhhn." But with the word "penn," you say it quickly.
The easy thing about Norwegian is that there is no verb conjugation according to the subject. So instead of I say, he/she says, it's just I/you/he/she/we/you all/they say (or should I say jeg/du/han/hun/vi/dere/de sier).
Another difficult thing is that there is no clue for figuring out if a noun is masculine, feminine, or neutral. In Spanish, for example, you can usually tell that a noun is feminine because it ends in "a," like "la rosa," and it is most likely masculine if it ends in "o" like "el libro." Not so in Norwegian. Our professor basically told us that you just have to memorize each noun's gender. So with the word "lue" which means beanie or hat, there is no way of knowing if the indefinite form is en lue, ei lue, or et lue (it's ei lue, but there is no explanation why). This seems like it would be an issue even for native speakers. What happens when you learn a new noun but mistakenly get the article wrong, or you just forget what the correct article is, and you sound like an illiterate idiot for saying et lue instead of ei lue?
Next difficult thing: telling time. If it is 3:30, the correct thing to say is "klokka halv fire" (half four). This is confusing, because half four seems like it would be 4:30, right? There is a hilarious exercise in the book where a non-Norwegian guy agrees to meet a Norwegian girl at "klokka halv sju," so he waits for her at 7:30. It then says he goes home sad, not realizing that they were supposed to meet at 6:30.
Those are the ups and downs of learning Norsk, and I'll leave you with some cool Norwegian words.
-pappapermisjion: paid paternity leave
-pysj: pajamas
-å love: to promise
-kjempefin: super fine
-applesin: orange (fruit)
-eple: apple