The spoken grammar of Japanese isn't too bad. I'd say it's more logical than English overall.
Written Japanese in Hiragana and Katakana is unambiguous in spelling/pronunciation. It's not like English where you need to learn a bunch of spelling (and sometimes multiple spellings). So it's massively easier.
There's Hiragana and Katakana which have a similar purpose, but then English has upper and lowercase letters for seemly no very useful reason.
Kanji is a significant additional workload and there where efforts to get rid of it in the past. The problem is I'd guess it does have utility, cramming more data in per unit area is useful, as is being able know it mean "on" or "off" or "of passable quality". And now with computers you can type in Hiragana and it prompts for the Kanji. That makes things significantly easier.
The other thing that's interesting about Kanji is the meaning is divorced from the sound. With English your forcing a discretized serialization on sounds. With Kanji the idiographic communication feels closer to a visual representation of a concept.
The stroke order seems annoying at first, but it's pretty consistent, and actually really helpful for memorizing. The different pronounciations also seem intimidating at first, but for the most part:
- One's for composing with other characters
- Others are mostly variations on that one for fluidity, where people will still understand you if you get it wrong
- There may be one for when it's used on its own, that gets used so often you quicly think of it as basic
- Anything else is probably an edge case that you'll never see
tl;dr: Don't let the Kanji intimidate you
A Chinese reader could wonder why we use multiple glyphs to expose a single concept. "How inefficient," they might think, "each character has so few bits of information! Are speakers of this language just memorizing entire blocks of characters at a time so they can read fast?"
Of course, the real winner of this argument is probably Korean.
I think proportional fonts have a better space utilization by their nature. Anyways, I don't think that's an important metric. It's not like we live in an age where paper is scarce.
But, much like English, if you want to know all the subtleties and intricacies: strap yourself in, we're in for a rough ride. There are lots of finer details you can get lost in, just like any established language.
It's much easier than language like Finnish or Russian in some respects (lots of things like needing to match genders, modes, plurality, etc. simply don't exist in Japanese), but then there are also things that are much harder (like knowing which level of politeness to use when talking to someone).
It's all about what you consider "knowing Japanese". Microsoft could never hope to come up with something as convoluted as Japanese, or even modern English. They're both waaaay more nuts if looked at in their entirety =P
Although the writing system is a PITA. It's of great cultural value etc. etc. but it presents a huge barrier to learners.