Agreed. In particular, as a philosophy student, I would add that there is very little on LW that I would class as original philosophy. A lot of it is presented well, and in a way that is accessible to people who aren't familiar with the language and literature of modern analytic philosophy. However, most of these issues have been discussed by analytic philosophers in some detail.

e.g. this post and the following discussion makes a pretty good effort at embedding Eliezer's metaethical position into the usual metaethical landscape. Sure, there's disagreement about it, but the discussion certainly can, and has been, phrased in those terms.

So I would certainly say that LW has provided me with some useful perspectives on some philosophical issues, but you can find most of the material in analytic philosophy if you look. True, there's a whole load of tripe to wade through, but there's something to be said for the discipline of really understanding why everyone else is wrong! And if you're of an analytic/logical bent, you'll probably tend to gravitate towards that part of the literature anyway.