That was just....ugh. The acting and dialogue were appalling. It couldn't look any more cliched. It's like if Starship Troopers was played straight. I admit that the scenes where the Covenant are attacking seem intriguing, having Chief so up just as fan service was cringe worthy. The best Halo game story was ODST, and that's because we had likeable cast of regular soldiers, not the superhuman automatons that are the Spartans. Also, we know Chief lives, so where's the suspense? It might be a bit more intense if there's a chance for the superman protector to possibly die. Also, doesn't this conflict with the idea that Harvest was the first fight with the Covenant? Am I supposed to believe that even after Harvest the military was still totally ignorant to the existence of hostile aliens? I'll probably watch it out of curiosity, but I don't predict I'll enjoy it.
As a side note, it kind of annoys me when people tell others that "the Halo story isn't bad, but you just don't get it because you don't read the books!". The games' story, while not BAD per se (except for the mess that was Halo 3), are far from good and are basic generic sci-fi. If they need several books to fill in the blanks, then that's a flaw with the delivery of the games. One shouldn't have to read several novels, watch an animated movie, and use a Ouija board just to make the plot stand up.
Something else that just stuck out to me as I rewatched it to finalize my thoughts. Is it only Chief there? If so that will be facepalm worthy. Spartans were NEVER sent in alone like that, and prefer working with each other rather than regular troops since regular troops can't keep up. Again, it makes everything feel even more like fan service. And if they play on the idea that whoever survives this and MC know each other in Halo 4, that will make me even more annoyed at the idea I talked about in the previous paragraph. If to understand the scope of everything going on I need to play the games, read the books, watch the short film, read bonus material, and then sort out what is canon and what is not (the Halo series plays pretty lose with it's canon), then that means the plot of the game FAILS.