Card draw has always been considered one of the most powerful effects in Hearthstone. That's why minions like The Curator and the pre-nerf Ancient of Lore were such great cards.
Countess Ashmore is very similar to The Curator in this regard, and may draw three cards on turn seven. The only drawback is that it has no Taunt, but this time, the attack is higher.
It's hard to say which one is better -- the Taunt or the attack -- but in any case, if you properly build your deck around this legendary, you will get some really good results.