I'm not sure where you get this information from. The train takes 20minutes and couldn't be easier as it goes from beneath the arrival hall and drops you off at the heart of downtown . It's a bit pricey with abt 20 EUR per direction (-50% for students) but something I'd gladly pay to avoid spending any extra time at ARN, which even with lounge access is nothing to write home about. Stockholm on the other hand is beautiful and highly recommended!