It's actually a prequel to the other Halo games.
[spoiler alert!]All spartans except Master Chief die.
Though, it has been stated that the Halo series will continue, but Bungie won't be behind it anymore. They will continue to run the servers for the already existing Halo, the exceptions being Halo 2 and Halo Wars(The only Halo game to date not created by Bungie). They just decided to shut down the Halo 2 server not long ago but Halo Wars was made by Ensemble Studios.
Also: Halo Reach releases at midnight! I'm so excited for it that I'm shaking a little! I'll be at the midnight launch, but if you pre-ordered it, you can go and collect it at any time at the 48 hours after it launches, otherwise, they'll sell your copy to the next in line.(assuming of course you DID preorder it)
Another few fun facts that I forgot to mention about Reach are the new and improved Forge 2.0. They have enhanced editing features, such as being able to lock an item in place instead of having to stack it on top of stuff and delete the stuff under it. Snap-to's, where you can snap it in 45 degree or 90 degree angles and also where you can fine tune the details to get the map piece exactly where you're wanting it. Also newly introduced to forge is phased mode, which allows you to do the same as the fixed mode I stated above, but, you can merge it with other objects or stick it through other objects, it will allow everyone to be way more creative in their designs and also allow for much smoother maps.
Also they have Forge World, which is essentially 5 maps combined into one. You can make your map anywhere in this forge world and do anything you want in it.
Also in Reach, your Spartans will be WAY more customizable and you can let your creativity shine through them. Also notable, your spartan you create for multiplayer will be how your character in the campaign will look. Also available are voices that you can assign to your character that will be in use in firefight modes. With voices such as Sargent Johnson, Buck(ODST), Cortana, and Master Chief, how can you go wrong? Note though, that these voices are quite expensive, and it will take around a week for a normal casual player to unlock one.
I think that I've said enough for now, see you in the field marines.
