If you've logged more hours playing Halo on Xbox Live than you have down the pub; if you bought Halo Wars and actually played it to the end; if you know your Rooster Teeth from your This Spartan Life, then why are you reading this review anyway, as you've probably seen most of these short Manga films on Halo Waypoint?
For the rest of you, this may need some explaining. You may have clicked onto this without realising it's a DVD not a game. The basic history is that Microsoft set up a company called 343 Industries to manage and promote the Halo brand. 343 commissioned seven short films from top anime studios, and the resulting short films were premiered on Xbox Live (via the Halo Waypoint add-on) in a one-day window. Each film ranges in length from around 10 to 20 minutes.
Although the stories are described as being canon (with the exception of one film, which is a parody), they often explore areas of the Halo universe and mythology outside the storylines of the games, though there are also many encounters with characters you'll recognise. The style of animation may sometimes seem at odds to some people with the western influences of the game, but for the most part that works well and gives a new take on it. Sometimes it doesn't work at all - for example, The Duel is basically Elites turned into Samurai, and although it is the first time we see female Elites they are more human in feature than Elite and extremely subservient. But the good thing about this compilation is that there may well be episodes you hate, but there are bound to be ones that you love.
It's not an essential purchase, unless you're a serious fan of the game, but it comes recommended as something you may be glad you took a chance on.