I've read a few raptitude posts. From the tone of his writing, it seems that he is mostly just sharing his own. However, the subtitle of Cain's blog: getting better at being human could be read as instructional. It could also be read as simply reflective, so I guess it depends on the reader's perspective.
Since Cain promotes a minimalist, conscious-raising, zen-like approach to self-improvement, I find it much less offensive than those with instructions for fame and fortune. Even so, I just reponded to a raptitude post here (which made me remember this question), and in this case I think the strategy could work for some, but not others, although Cain doesn't suggest it. IMHO I suppose if you approach Raptitude as a source of new perspectives, it could be helpful. But there does seem to be an implicit buy-in there.
In short, I guess it always depends on the reader.