My biggest problem with the Crota fight, especially on hard, is it's not particularly fun. It seems way too mechanical to me. On hard, most of the time you're not even shooting anything most of the time, at least if you're using the most common strategies. Just managing health, orbs, and time. Probably will not go back to hard Crota very often once I get the scout.
Also, the bugs and lag seem on another level compared to regular Crota or Atheon. Someone joked tonight that they kick in once morale is too high. I am normally not one to harp on lag or bugs as excuses, but it's fairly bad from what I've seen.