Meh, the storytelling could get overwrought and some of those cutscenes in 2 should have been cut down or cut out entirely, but I would still say that as a whole the plot of the Halo games, and especially 2, was a fundamental part of its success. Halo 2 was what sent Halo from generic "shoot aliens on an alien planet" game to "epic multi installment space war".
Obviously there are plenty of games that "do it better" e.g. every rockstar game but my personal opinion is that Halo is awesome. Totally subjective though.
I think that might be where 343 went wrong, though: they correctly recognized Halo had narrative value, above many other action series in fact, but then thought they could make it better by making Chief a pussy or Cortana emotional. The space opera was good enough. That's also why the best parts of Reach were "everyone is dying" and not "no, generic teammate death!!" scenes.