The main two features that come to mind are the ability to edit a card once it has been published and the ability to make a published card private
Blame power creep, or the aggressive nature of the best MTG Arena decks right now, but it seems unlikely to me that many decks can cope with a two-drop on their own side of the field that continuously blats them in the face for large chunks of damage
The addition of all the enchantment and artifact anthems means you can more usefully develop board state while waiting for that critical board clear to go off
These playable cards include all the necessary details, from the cost at the top right to the effect description hand written
Duskmantle Guildmage also works to turn mill into damage, once you can activate its ability
Decks that go wide with creature tokens aren't too heavily impacted by this, but still, the Winnower is a fine start