Just going to be a bit nitpicky here. Noun declension is a feature of various non-slavic languages, including Latin which English speakers have a decent chance of having been exposed to.
Modern Russian has 6 cases (with a couple more that pop up very rarely) with 3 genders and singular/plural endings. It's a total of 36 possible combinations, which is not that bad. Masculine and neuter also share most endings so there aren't actually 36 unique ones
Probably the most difficult thing about cases when I was learning Russian was remembering which verbs took a different case than I would expect, e.g. dative instead of accusative for what seems like a direct object.
Right: but one difference (which you sort of hint at) is that German is consistent in why something takes a particular case compared to Slavic languages (e.g. direction vs location), and at least the preposition is consistent. Is it "nad morze" or "nad morzem"? No way to know without the entire sentence. And "morzem" is the "tool case" -- the form you usually use to describe that something happens with the help of a tool even though the sea (morze) is not at all a tool in that sentence. Oh, and you only use "nad" with bodies of water by the way. Sorry!
Another incredibly tricky one for Slavic languages is imperfective vs perfective aspects. In most other languages, perfect vs imperfect is just a standard construction. In Polish (and Russian, though my examples here are Polish), you change the verb itself. How? Well, sometimes you put "po" in front of it, like rozmawiać / porozmawiać. Sometimes it's "z" (jeść / zjeść), sometimes "u", "na" or "wy". And sometimes you just give up, like oglądać (but obejrzeć in the perfective), widzieć (zobaczyć), mowić (powiedzieć).
(For this reason I have found it very hard to progress in Polish without conversation with native speakers who aren't too polite to correct me.)
Yes, perfective and imperfective aspects are very tricky, particularly how they interact with various other linguistic features: imperatives (and the negative imperative), the subjunctive, and verbs of motion come to mind, each of which modifies the use of the aspects in it's own way.
> Modern Russian has 6 cases (with a couple more that pop up very rarely) with 3 genders and singular/plural endings. It's a total of 36 possible combinations, which is not that bad.
36 isn't that bad but Russian also has 253 irregular verbs [0], each of which adds another set of combinations. A lot of them are just small tweaks and there are some that follow a set of patterns (e.g. идти with its various prefixes) but it still adds a lot of overhead.
Modern Russian has 6 cases (with a couple more that pop up very rarely) with 3 genders and singular/plural endings. It's a total of 36 possible combinations, which is not that bad. Masculine and neuter also share most endings so there aren't actually 36 unique ones
Probably the most difficult thing about cases when I was learning Russian was remembering which verbs took a different case than I would expect, e.g. dative instead of accusative for what seems like a direct object.