100% on this hill.
One of the very few games as a total package was worth every penny of my 69.99 (steel book in CAD) from that time.
Full fledged campaign, with local and online co-op w/8-10 hours run time, added replayability with addition of skulls/game modifiers.
Robust multiplayer w/ several maps and future DLC content - various game modes and support for local and network play- inculding local splitscreen to online multiplayer
Multiplayer with cosmetic unlocks - no MTX
Full fledged theatre mode across campaign and multiplayer - w/ server browser like interface to see full clips from entire multiplayer or campaign sessions
Full fledged map editor/maker in Forge mode- leading to many game modes that are staples of the franchise today - Griffball, firefight (early iterations)
At the time of its release- banging visual fidelity (minus character faces lool - cant win everywhere)
Honestly- not a single game i have purchased since then, including other Halo titles have ever felt as good to play as a completely out of the box package. Gaming after 2007 imo, began a downward trend.