Are you looking specifically for "crunch" (actual stated things, like weapons, spells, NPCs, etc) or are you also looking for "fluff" - descriptions, locations, etc?
Because in terms of crunch, there is very little out for SR5 at the moment, since it just came out. But if you want to look at fluff, there are TONS of books written for SR4 that totally still apply. All of the Location books are great (Seattle 2072, Runner Havens, Montreal 2074, The Land of Promise, etc), . You also have the aforementionned Sim Dreams and Nightmares, but also stuff like Vice and Corporate Guide, which talk about Organized Crime and the Corporations respectively - indispensable info for getting to grip with the denizens of the world of Shadowrun. The 6th World Almanach, of course, good book to have around.
These are all books that are not out of date and well worth reading for new players.
There is also the line of short story fiction, great for understanding the tone of the world.