I have been an avid fan of the Halo universe since its inception.
This is worth watching. While it is easy to be deterred by sentiment to the original Halo; Combat Evolved story, which is yet to be seen, patience is key. It is obvious from even the first episode that the producers have taken every effort to accomodate the entirety of the Halo universe and lore, using a lot of source material in order to ‘set the stage’ in a simple, progressive, yet engaging adaptation.
Im wary of what might come given video game adaptations have often been unsuccessful or disappointing; but so far Paramount has made an awesome start, personally im eager to keep watching and to others id simply say you no matter what your opinion is after; you wont regret giving it a watch. If you are loyal to strictly the game story elements only, you might be confused or disappointed even, but if you keep on open mind to the larger story and can see how well the plot is already forming; id daresay you will watch and want to rewatch!