http://hubpages.com/hub/Most_Difficult_Languages_-_Polish
That`s interesting. For me even English is hard to learn. Now I`m learning Norwegian, it`s not that difficult but extremely hard to pronounce, especially when each city has its own accent.
I`m learning bokmål, but working in Ålesund I can`t understand a word of what people say.
Faen!

Any language developed in a region that is geographically unconnected to you is hard to learn. For me, a native English speaker, most Romance languages (languages based on Latin) are simple enough, Arabic is a bit tougher, and Chinese is right out.

Kærravolinj du å sjer æ, tru du må få dæ litt hembåkkåkaku frå førvukkjun attåt åbiten i mårra tile, æ!

Frisian (and I'm from Friesland).

Not 100% sure about this, but Czech should be one of the harder langues.

Haha, as a Pole I learned a few things about the months that I didn't know (or hadn't noticed) before :P
Although I always thought (and have been told) that my first language is kinda hard if you try to learn it through theory, I'm pretty sure there's some harder languages out there.

ماذا قولت؟ لا أقول اللغة بولندي

The first thing you learn is, for some reason, how to swear properly. At least that's my experience in observing introductions between youths of different nationalities. (Me, I don't swear if I can help it).

Yep, Google Translator not gonna help I guess.
Taki cwaniura a ciekawe czy by wyrecytował w Szczebrzeszynie chrząszcz brzmi w trzcinie, albo stół z powyłamywanymi nogami.
I can watch Krtka without translation ;)

Its difficult to say what language is the hardest to learn. There are languages that are easy to pick up on pronunciation and basic sentence structure, but is near impossible to master the nuances and different proper uses of words in certain situations, while other languages are difficult to pronounce off the bat but are fairly simple in usage. I'm Finnish, am fluent in English (live in New York), and have tried learning Japanese. English is kind of a bitch to learn to pronounce correctly, but fairly easy to get the hang of once you overcome the spelling and pronounciation issues (since you basically just have to know how to do things rather than learn). Japanese on the other hand, is easy for me to pronounce, but the goddamn sentence structure and levels of formality will make it probably very difficult for me to ever master.
chinese would probably be out for me, I don't think I could pronounce anything even remotely closely. Difficult is in the eye of the beholder.

Dævendøtte sykkelstøtte, det tok mæ et par lesninga av det der får å skjønn nå.

I hear people saying that Portuguese is a pretty difficult language, but I wouldn't know, since it's my native language. I'd probably say it's Chinese or something like that.

I think in many cases it's very much a matter of how different the language you're trying to learn is from your own. Danish is said to be very difficult to learn, and I can understand why. However, for other Scandinavians it's probably not so difficult, as it's very closely related to the other Scandinavian languages (except Finnish). For an East Asian however, it would be a completely different story. The East Asian languages are constructed completely differently from the European languages, so I think that's where the greatest difficulty lies, across completely different language families.
Ironically, written Norwegian is almost identical to spoken Danish.

Binary is easy to learn ... But hard to master!

German probably.
It's a fucking ugly language and it has so many special cases, and our grammar isn't consistent as English or Latin.
Be glad you never learned it.