Even if you're not a roleplayer, the guides are fascinating. They're well-written, thoroughly researched, and a supremely entertaining (and sometimes funny) guide to the mindset of each race. The guides also give some background into how each race arrived at the perspective that it did, and points out that there are several race combinations (notably Tauren/Gnome and Troll/Draenei) who really know very little about each other, and must rely on the often-biased opinions of their faction colleagues. And even beyond that, it keeps digging into the shifting nature of politics within each faction: why are the Forsaken and the Blood Elves on shakier ideological territory with each other now? Why are the Night Elves so standoffish with the Alliance as a whole, and why do the Humans in particular react badly?
I honestly can't say enough good things about these guides. No, they're not official lore, and there's necessarily some conjecture based on game mechanics and vague ingame hints concerning what's going on, but they seem pretty damn accurate to me. If you're in any way interested in Warcraft's lore, or in understanding why certain things in the game work the way they do, the full list of guides is here.
If you're interested in roleplaying your race and class in-game, check out our own series of guides, All The World's A Stage.