Trying to encompass all of the mythology of Tolkien's Silmarillion is an epic undertaking. To screenwrite it in a way that slowly uncovers the underlying, and deeply interwoven storylines while holding the audience's attention is a monumental task. While it may appear that portions of the story are being omitted or glossed over, I don't believe that to be the case. Rather, it seems, after three episodes, the writers are teasing out these storylines with glimpses, flashbacks, and foreshadowing.
The cinematography is grand, very in keeping with the visual scope of the movies. The character development is well-paced, if a bit overwhelming at times with so many storylines (not unlike the book itself). But the story -- so far -- literally drips with Tolkien authenticity.
Some will say it's too slow and convoluted. In today's cinema where "action" and six-second cutaways have become the norm, I welcome the pacing. Some will say there are too many divergent storylines at once. But, like the book, these are all moving toward a convergence. Some will say there are key elements missing (the Simarils), but these are already mentioned and hinted at in episode #3.
I, for one, am thoroughly enjoying this series, and cannot wait to see where it goes next! If you're a fan of Tolkien, and if you've ever tried to pore over The Silmarillion, I think you're in for a wonderful ride. (Of course, after only three episodes, this is only speculation -- for now.)