"The spells of the Mark" feature actually looks like a pretty significant buff to dragonmarked spellcasters - especially sorcerers. - edit maybe not, it only adds to the class list, not spells known. But Mark of Finding gets Hunters Mark now? That's pretty good, even once a day.
Mark of Mending is nerfed, but I did think it was OP.
Kalishtar no longer need to use their reaction to gain advantage on wisdom saves.
Mark of Warding looks buffed. Bonus on thieves tools and investigation, mage armour (once per day is plenty) and Armor of Agythys on your spell list? What's not to like?