General beta feedback regarding difficulty
I see that this course is still in beta, so I just want to give a bit of general feedback (intended as constructive criticism, not just plain criticism):
For me, at least, this is much, much more difficult than any other Duolingo course I've tried.
I imagine that at least some of that is because Klingon was designed to be "alien". But I don't think it's all because of that: I'm OK at French (and was so before Duolingo), so it makes sense that would be easy for me, and Duolingo Spanish has been mostly easy probably due to similarities with French and also due to general exposure that you can't help but get a bit of in the US. But I'm also trying Russian, which is in a lot of ways totally foreign to anything else I know. Duolingo Russian is much easier than Duolingo Klingon.
It really seems to me that there's just so much jammed into a small number of lessons (relative to the other Duolingo courses). I'm constantly wondering, about lots of different things, "When did I supposedly learn that?!". But regardless of whether it's true that there's more stuff jammed in here, or if it's just that it's more difficult due to the "alien" design, perhaps you should at least consider slowing things down, spacing lessons out, and giving a lot more repetition for basic concepts.
I understand the too slow book, but since this is an "alien" language, could you make an introductory lesson that tests the pure basics first, then compounds them in a later lesson? You guys are doing a great job considering you have a good, clear voice for the words and sentences.
Sometimes I forget to read them when first starting a new lesson, but yes, I've read them all, and I sometimes go back and re-read them too. I don't want to say they're not helpful, because they do help, but... like I indicated, I'm finding this more difficult than other courses, and that's with them.
When I said "I read them all", I meant all of them up to the lesson that I've currently made it to, not literally all of them.
I actually found the Klingon course, which I started when it first came out with no prior exposure to the language, very well paced compared with some other Duolingo courses. Reading the Tips & Notes is essential, though.
If you want an example of a course that really does too much, too fast, try Hungarian. :-)