metal_wrath
I dip my forefinger...
I think Finnish and Hungarian are usually considered the most difficult non-Asian languages to learn (they come from the same language branch). Czech has seven cases to the 21 (I think) of Finnish. That has got to be a pain in the arse.
Basque is considered very difficult possibly more so than the Finno-Ugric languages.
The many different cases for words seems unneccesarily complex in many languages.
Esperanto allows for only a few forms for each word.