I actually have a pair of canvas work pants - not jeans, but pants made of canvas - so as far as I'm concerned, it doesn't work to refer to modern jeans as canvas pants. Many languages seem to have taken some form of "jeans" as a loanword anyway.

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On building vocabulary - I found this absolutely the most difficult part of reaching a good level of fluency. My vocabulary for things like plants, animals, etc, is also rather small. I think that reading helps, especially if you make a point of reading literature (not news articles) and if you make a point of looking up words you don't know (even if you are already a fluent speaker).

I learned "pajlo" (straw - like straw in a barn, not what you drink from) from "La ŝtona urbo". The wider range of your reading, the more you pick up words. This is something I haven't done as much as I ought to, I admit.

erinja:On building vocabulary - I found this absolutely the most difficult part of reaching a good level of fluency. My vocabulary for things like plants, animals, etc, is also rather small... I learned "pajlo" (straw - like straw in a barn, not what you drink from) from "La ŝtona urbo". The wider range of your reading, the more you pick up words. This is something I haven't done as much as I ought to, I admit.

For what one might call "immediate environment vocabulary" I found "First Thousand Words in Esperanto" most helpful. From that book I learned 'pajlo' and also the contrasting 'fojno'. I take indecent pleasure in being able to name in Esperanto almost everything around me, even if my oral skills and grammar leave a (-n awful) lot to be desired.

erinja:
On building vocabulary - I found this absolutely the most difficult part of reaching a good level of fluency. My vocabulary for things like plants, animals, etc, is also rather small. I think that reading helps, especially if you make a point of reading literature (not news articles) and if you make a point of looking up words you don't know (even if you are already a fluent speaker).

I learned "pajlo" (straw - like straw in a barn, not what you drink from) from "La ŝtona urbo". The wider range of your reading, the more you pick up words. This is something I haven't done as much as I ought to, I admit.

I certainly agree that for most of us, reading literature is the only way to build vocabulary beyond the intermediate level. As sudanglo pointed out, we don't have the option of hanging out with fluent Esperanto speakers and absorbing what he hear. Even reading and looking up words leaves the problem of retention, unless we manage to use the words a few times, to lock them in.

Lately, I've been using the Anki flashcard web site, and the corresponding app on my phone. Somebody has created a BAZA RADIKARO deck with 5,800 cards, and I'm working my way through it. It's very useful because after each card it asks you how easy that word was. Your answer determines how soon you see that card again. At the moment, I find this to be the best ready-made solution to the problem of building vocabulary.

But it isn't as simple as that CD.

Unless you are already a polyglot, you don't know what forms can be admitted under rule 15, and if you have never actually heard another Esperantist talking about his (or her) jeans, and you can't find it in your dictionary then you don't have a form immediately available for you to use.

The difference is that if you were learning French, you could just ask a Frenchman and he would immediately reply 'un jean'.

Prior to la Praktika Bildvortaro you might have said Bluĝino (a form registered by Waringhien) and even after 1979 using a different dictionary you might have come up with Ĵinso.

Whilst the problem of what to say for jeans might be considered as definitively solved now by ĝinzo (now registered in NPIV), there are many commonplace things which Esperanto may not have evolved a term for and can't necessarily be accommodated under the word-building system or under rule 15.

jchthys:

tl;dr If you already know a foreign language, Esperanto is relatively easy because you already know what a foreign language is like; you've "unlearned" your native language, so to speak, and have little to learn in the way of new idioms.

If you don't already know a foreign language, then Esperanto is relatively easy because unlearning your native language is pretty much your only barrier to break through, and you don't have to spend lots of time learning the "Esperanto" way of doing things.

If I were to learn Finnish, I would not only have to unlearn English: I'd have to learn not only Finnish words but also a great deal of Finnish syntax and "the way you say things in Finnish"—the myriad of little rules about what is idiomatic and what's not.

I agree with all you say, just that you should have chosen another example instead of Finnish. Finnish is very Esperanto-like. When the modern Finnish "culture language" was created in the nineteenth century, it was an effort of language planning to an extent which is quite uncommon. Rules were formed based on logic rather than usage. Even a new phoneme was created /d/.
When it comes to Finnish of today, the written language has still much of this freedom from idiomatic constrains, while popular language is developing away from it.
What still makes Finnish much more difficult to learn for everyone with a background in European languages, is that loanwords from Greek, Latin and French are so few. Finnish grammer is also, though its logic, much more complicated than Esperanto grammar.

In some respect there are no simple and no difficult languages in the world. All languages tend to develop until they coincide with the full mental capacity of their speakers.
We can observe this process within Esperanto now. It has been developed to be easy, but there are many users who want to express their skill by inventing/exploring/introducing new distinctions and nuances. If we want to preserve the simplicity of the international language, we must be aware of this desire among the users (including ourselves) and lead it into constructive orbits.
That said, languages do differ when it comes to how difficult they are to learn, but for a judgement we have to specify 1) to which level one intends to learn the language, and 2) what is the learner's linguistic background.

What is a "ratchet spanner"? That I don't know this word in English, a language that I use every day, is a good point, thanks! (Don't remember who wrote that so far back but, good point!)
We are off to Brazil in two weeks and I claim that I speak Portuguese - but I am constantly forgetting the word for "bradipo" (slough) even though that is a common animal in Brazil. Does that mean that Portuguese vocab is really harder than Esperanto? Hehehe - hardly! It is just that I know a guy here named "Brad" and he is a bit of a slough and so that strange word has stuck in my brain while ("whilst" for the GB crowd) the Portuguese word eludes me.
As far a vocab memory goes, I think that all languages that are not similar to one already known are hard. Chinese grammar is pretty simple but Chinese words are hard for me to remember except those that I use often or that are particularly funny (Like "茄子" which means "eggplant" and what is what you say when they want to take your picture).
Esperanto is a language and vocab is part of the baggage in acquiring a language. Smile! 茄子! (quiezi)

robbkvasnak:Smile! 茄子! (quiezi)

Cheese!

I just learned a new English word reading Esperanto. In "Vivo de Zamenhof" the words "litvo" and "litvano" both seemed to refer to Lithuanians, but not interchangeably.

I found that "litvano" translates as "Litvin", a word I didn't know. It's someone who lives under Lithuanian rule but isn't an ethnic Lithuanian.

Bruso:In "Vivo de Zamenhof" the words "litvo" and "litvano" both seemed to refer to Lithuanians, but not interchangeably.

That is strange, as:
1. the root is LITOV/
2. the "Litvin" should be a litovujano (or, my brain protesting against my fingers typing this, a litoviano)
3. litovano doesn't make a lot of sense, it's a member/supporter of a Lithuanian.