The weirdest thing about Finnish cases is the counter-intuitive nature (to a speaker of almost any indo-european language). For example: "dog" is "koira", "I like" is "pidän"; "I like the dog"? — "Pidän koirasta", which is using the "-sta/stä" ending of the elative case, which usually means "from". So, it's "I like from the dog". It doesn't end here...
* Tulin Norjasta — I came from Norway.
* Pidän Norjasta — I like Norway.
* Puhu Norjasta — Talk about Norway.
How come the same case is used in these?!
"Löytyy apteekista" — "Can be found at the pharmacy", literally "Find from the pharmacy". Saying "Löytyy apteekissa", which would literally mean "find at the pharmacy" is grammatically incorrect.
So, yeah, Finnish grammar is nicely structured and consistent, but sometimes it just goes against intuition of speakers of other languages.