What languages do you speak? I speak Spanish and have been learning Polish for a few years because my wife's family immigrated from there, and many are still in Poland, with some only speaking Polish... can't have the in-laws talking trash without me knowing :)
Spanish is generally straightforward and consistent, though the huge number of dialects can be a challenge for practical communication.
Polish is a goddamn nightmare. I thought English was bad, but hoo-boy, Polish haunts my dreams. To say it is needlessly complex is an understatement. You have to change the endings of adjectives/nouns to match the context, so you end up with a ridiculous number of forms of each word.
"Dog" is pies (pronounced pee-yes, sorta). Unless you use it in the sentence "I have a dog," in which case it is psa (puh-sah, again, sorta... I don't even know how to type out some of the sounds phonetically). If you say "Cooper is my dog" then it's psem.
Depending on who you ask, there's somewhere between twelve and twenty ways to say the word two in Polish (and just to be clear, most of these counts don't include things like both, pair, etc. - just literally the word two).
Then there's the specificity of the verbs of movement. Oh my dear lord - the verbs of movement.
You see, you can never say that you went somewhere or that you're going somewhere. You must specify how. Always. You cannot go to Poland, you must fly to Poland. And every verb of movement has at least two, usually three forms. To fly is latac or leciec or poleciec, depending on whether you flew once, you flew regularly, or you were flying when something happened. The last one is a situation in English that we'd just handle with a form of "to be" and a gerund - "I was flying when..." In Polish, you have to memorize a specific version of each verb for that form.
Add to that the fact that my Polish teacher's explanation for many things is "there's no rule, you just have to learn what sounds right." In one case, if you have a masculine noun you must either add an a or a u on the end. There is no rule for which.
It's like they designed the whole thing just to be a nightmare for any non-native speaker trying to learn it.