I had considered making my own version of L4B to take care of some things that, personally, put me off.There were a couple of Excercises that were "gotchas" and you don't want those in learning material for beginners
(Mistranslating taipei under the auspices of "a b sounds like a p in the local orthography" is a terrible excuse and it made it sound like Robin was showing off)
Of course, by reading this board for several months I know it wasn't intentional.
Some other recommendations:
1) Try not to emphasize the concept of malglico so much. You have to explain lojban in English terms in order to teach it to an English audience, so translating ninmu to x1 is a woman and scolding the learner for assuming it means an adult isn't right (by the way, we have a word for ninmu, its called female).
2) Find ways to explain the concepts without resorting to "If you're a Mathematician, computer programmer, or a logician, its like these things."
3) Concepts and words related to language studies are confusing, please give some kind of definition for these concepts.