The first episode seems like it does not stay true to the source material. With the gradual development of plot (like all shows), it is completely congruent with the comics (of which the 2009 Snyder film had a 90% congruence with). There is further development of characters that weren't ever expanded on in the comics (specifically Hooded Justice) which ultimately ties the current HBO series with the original graphic novel.
The show constantly is throwing twists and turns with an ever-evolving plot and very interesting characters. I highly recommend this show to anybody that is interested in comics or superheroes, impressive plots, or anyone looking to fill the void Game of Thrones has left us all with.