Keith,
Newbie lessons are very easy for me now
The Beginner series is suitably challenging, but I tried Intermediate S1 #1 just to see how I do. I found it difficult, except for maybe one grammar point. But then again, I studied it along with other lessons, so I think it was just too much stuff to absorb all at once.
I asked for Lower Intermediate so that I could have a challenge but not have it be overwhelming...this way I'm hoping to "ease my way in" to a higher level. But I'm sure the Beginner level won't start being "too easy" for me anytime soon.
By the way, what I found most difficult in that Intermediate lesson (S1 #1) was that the long sentences weren't broken down enough, and they should be said a little more slowly (not extremely). They are said very fast in the audio track. The words seem to just meld together.
I think at that level the dialogue should be broken down (said slowly) further than just sentence by sentence. I can't absorb the difficult words and phrases unless there isn't too much stuff being said right before them. Saying half a sentence or a third of a very long one at a time would be perfect. I have the same problem with some long Beginner level sentences.