Blitz Mode for is pretty fun, but I think it's going to be drowning in microtransactions for the cards. I mean, they're obviously going to be there, but doing well is probably going to mean acquiring a LOT of packs until you have a couple of decks full of rare cards. It definitely is an improvement over Halo 5's REQs since they are permanent cards, though it doesn't look like there is a way to craft them like Gears 4 or Overwatch, so you could potentially never get the stuff you want.
There is a Firefight in the options though who knows if that will have the same legs as normal Halo Firefight. It's nice to see this along with Blitz. Halo Wars 1 had a small but dedicated playerbase, but having more options might bring in more long-term players.
The art is encouraging to me. While some the Covenant and Forerunner stuff looks closer to 343's style, the Spartans and most UNSC vehicles look closer to Bungie and (Ensemble's) HW1 designs. The choice to set this after Halo 5, and at the Ark of all places, certainly is giving this potential to be interesting. I get the feeling they will just brush over the 30 year gap that the Spirit of Fire presumably cryoslept through, but even without building on that there could be a lot of interesting stuff here.
Personally I don't know that I'll stick with multplayer enough to care about the DLC for it. I hope you can just buy the story stuff separately. Currently you can't even get the season pass outside of the Ultimate Edition.