I have to say in regards to Warzone and Arena that they are the most enjoyable multiplayer experience I have had since Reach and 3, it is tight, fun and tense and I highly enjoy the changes that they have made (Universal loadouts, groundpound ect) and it is highly balanced. The biggest issue I personally have had with this game are the maps themselves, they are all very bland and I not unique in the slightest however, from a gameplay perspective they are good and all future DLC will be free. In terms of Campaign it is plenty like Halo 2 (though thats not a bad thing, Halo 2 is my favorite Halo) and as result has similar strengths and weakness'. The game also relies too heavily on the player knowing the established lore, so for players unfamiliar with the franchise lore i'd imagine the story and characters would come across as bland.
Overall, good game and highly enjoyable and I would recommend if you own an Xbox One.