I don't think the cases are ultimately the difficult thing - it's some upfront work, but ultimately Finnish is agglutinative. That is, one adjustment to a word

I don't think the cases are ultimately the difficult thing - it's some upfront work, but ultimately Finnish is agglutinative. That is, one adjustment to a word does one thing, and no more, unlike Romance languages. The langauge is also pretty regular, and whether you're using puhekieli (lit. spoken language) or kirjakieli (lit. "book lamguage"), what you see written is what you can say and be understood. Some often not mentioned difficult parts include the fact that Finnish has both front and back vowels, and that the language allows you to use long vowels and doubled consonants very freely, which makes it difficult for a foreigner to pronounce.